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UBC Theses and Dissertations

Secondary autogenic succession in the southern Rocky Mountain Trench Kemper, John Bryan 1971

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SECONDARY AUTOGENIC SUCCESSION IN THE SOUTHERN ROCKY MOUNTAIN TRENCH by JOHN BRYAN KEMPER B. Sc., U n i v e r s i t y of B r i t i s h Columbia, 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Plant Science We accept t h i s t h e s i s as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA APRIL, 1971 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely ava i lable for reference and study. I further agree that permission for extensive copying of this thesis for scholarly, purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver 8, Canada Date / , //// 1 i Frontpiece: Premier Ridge, one of s e v e r a l c r i t i c a l w inter ranges f o r w i l d ungulates, which e x i s t on the f l o o r of the southern Rocky Mountain Trench. The western edge of the Rocky Mountains, Hughes Ranges, may he seen on the r i g h t of the p i c t u r e . I i i ABSTRACT SECONDARY AUTOGENIC SUCCESSION IN THE SOUTHERN ROCKY MOUNTAIN TRENCH The patterns and ra t e s of f o r e s t regeneration on a c r i t i c a l w i l d l i f e w i n t e r range on the f l o o r of the trench, known l o c a l l y as Premier Ridge were examined i n t h i s study. A nearby western w a l l of the trench was a l s o I n v e s t i -gated to a s c e r t a i n the e f f e c t of e l e v a t i o n on f o r e s t r e -generation and understory p r o d u c t i v i t y . Forest regeneration i n a community which has remained unforested f o r s e v e r a l ' as years has pronounced e f f e c t s on the f l o r i s t i c dynamics and p r o d u c t i v i t y of the understory. On Premier Ridge the great-est f l o r i s t i c change was a r a p i d increase i n pinegrass and a. corresponding decrease i n the abundance of a l l other grass species as the f o r e s t regeneration progressed. Forbs v a r i e d widely In abundance whi l e shrubs were slower to react to changes i n the overstory. S i m i l a r trends were observed on E s t e l l a Mountain. P r o d u c t i v i t y of the grass component on the un-fo r e s t e d s i t e s was four times that of the forested s i t e s . The production of forbs and some species of shrubs a l s o de-c l i n e d as f o r e s t regrowth began. One spe c i e s , bearberry, increased under l i g h t f o r e s t canopies. The r e d u c t i o n i n p r o d u c t i v i t y and the changes i n species composition of-the understory which occur i n regener-a t i n g f o r e s t communities, appear to be d e t r i m e n t a l to f o r a g i n g i v p o p u l a t i o n s of w i l d and domestic u n g u l a t e s . C a t t l e seem to p r e f e r to graze the open, u n f o r e s t e d a r e a s , and as r e -g e n e r a t i o n proceeds, the acreage which they w i l l r e a d i l y use d i m i n i s h e s . Since t h e r e have been few r e d u c t i o n s i n stock numbers to compensate f o r t h i s range shrinkage, l o c a l o v e r g r a z i n g has become more widespread. The regrowth o f . the f o r e s t reduces 'the g r a s s , both i n terms of q u a l i t y and q u a n t i t y . T h i s Is the most important component i n the d i e t of c a t t l e and most of the w i l d l i f e s p e c i e s u s i n g the Premier Ridge a r e a . In a d d i t i o n , b i t t e r b r u s h , used i n the summer by c a t t l e and d u r i n g the w i n t e r by b i g game s p e c i e s , i s q u i c k l y e l i m i n a t e d by f o r e s t r e g e n e r a t i o n . Bearberry, which may be used by w i l d l i f e to some extent, i n c r e a s e s under f o r e s t cover. T h i s component does not approach i n -a v a l u e or u s e f u l n e s s , the l o s s e s that the o t h e r components repr e s e n t to g r a z i n g animals. The t r e e s of the south and southwestern aspects are c h a r a c t e r i z e d by r e l a t i v e l y slow growth r a t e s . Forage p r o d u c t i o n on these s l o p e s i s modest; i f g r a z i n g animals are deemed d e s i r a b l e i n the f u t u r e economy of the East • Kootenay, these areas should remain t r e e l e s s . Growth r a t e s are more f a v o u r a b l e on the n o r t h and n o r t h e a s t a s p e c t s , which are l e s s f r e q u e n t l y used as f o r a g i n g areas by w i n t e r w i l d l i f e , but may be used as s h e l t e r or bedding a r e a s . V TABLE OP CONTENTS Page I INTRODUCTION A. A r e a D e s c r i p t i o n and H i s t o r y 2 B. C l i m a t e . 8 C. The Problem 9 I I METHODS AND MATERIALS A. C r i t e r i a f o r S i t e S e l e c t i o n 1 1 B. S i t e D e s c r i p t i o n Techniques 1 3 C. D e t e r m i n a t i o n o f C h a r a c t e r i s t i c Stand Age 1 5 D. Annual P r o d u c t i v i t y Assessments 1 7 1 . Timber.... 1 7 2 . B i t t e r b r u s h and S o a p o l a l l i e . 1 8 3 . G r a s s e s , Forbs and Dwarf Shrubs 2 0 4 . B e a r b e r r y 2 0 I I I OBSERVATIONS AND RESULTS A. S i t e D e s c r i p t i o n s 2 2 1 . Skookumchuck P r a i r i e -The N a t u r a l G r a s s l a n d . . . 2 3 2 . P r e m i e r Ridge -N o n - f o r e s t e d S i t e s 2 5 3 . P r e m i e r Ridge -F o r e s t e d S i t e s 3 1 4. E s t e l l a Mountain -F o r e s t e d S i t e s 42 5 . E s t e l l a M ountain -Non-forested S i t e s 4 9 B. F l o r i s t i c Dynamics 5 ^ 1 . P r e m i e r Ridge S i t e s 5 ^ a . Grasses 5 6 b. F o r b s 5 7 c . Shrubs 6 0 2 . E s t e l l a M ountain S i t e s 6 0 a . Grasses 6C 1 b. F o r b s 6 7 c . Shrubs P7 v i Page C. P r o d u c t i v i t y 71 1. Premier Ridge 7± a. Grass P r o d u c t i v i t y 71 t>. Porb P r o d u c t i v i t y . . . . . . . ' 73 c. Dwarf Shrub P r o d u c t i v i t y 75 d. Bearberry P r o d u c t i v i t y 75 e. B i t t e r b r u s h P r o d u c t i v i t y 77 f. S o & p o l a l l i e P r o d u c t i v i t y . . . 80 2. E s t e l l a Mountain . 80 a. Grass P r o d u c t i v i t y 80 b. Forb P r o d u c t i v i t y 83 c. Dwarf Shrub P r o d u c t i v i t y 83 d. Bearberry P r o d u c t i v i t y 85 e. B i t t e r b r u s h P r o d u c t i v i t y 85 f. S o a p o l a l l i e P r o d u c t i v i t y 85 D. Overstory Community Composition.... 85 1. Premier Ridge... 2. E s t e l l a Mountain, G. P r o d u c t i v i t y of the Forest, 1. Premier Ridge , 2. E s t e l l a Mountain..., 85 87 E. S i t e H i s t o r y and Paths of Succession on Premier Ridge .. 92 F. S i t e H i s t o r y and Paths of Succession on E s t e l l a . Mountain 95 104 '10k 106 H. Aggregate Understory P r o d u c t i v i t y . . 108 1. Premier Ridge... 2. E s t e l l a Mountain 108 113 v i i L I S T OP T A B L E S Page I The Influence of c h a r a c t e r i s t i c stand age on the species dynamics of the understory grass species 59 I I The i n f l u e n c e of f o r e s t canopy on the percent ground cover of the grass component of the understory 59 I I I The abundance of shrubs on the Premier Ridge s i t e s , i n r e l a t i o n to c h a r a c t e r i s t i c stand age and f o r e s t canopy 66 IV The abundance of s e v e r a l species of grasses as measured by percent ground cover on E s t e l l a Mountain 69 V The abundance of forbs as measured by percent ground cover on E s t e l l a Mountain 70 VI S t a t i s t i c s f o r shrub abundance on E s t e l l a Mountain 71 V I I S i t e s t a t i s t i c s f o r t r e e s , Premier Ridge, 1969..: , 91 V I I I S i t e s t a t i s t i c s f o r t r e e s , E s t e l l a Mountain, 1969 93 IX S t a t i s t i c s f o r stumps, Premier Ridge, 1969 9'6 X Forest cover of Premier Ridge s i t e s , past and present 97 XI The paths of succession on Premier Ridge 98 X I I S t a t i s t i c s f o r stumps, E s t e l l a Mountain, 1969. 99 X I I I Forest cover of E s t e l l a Mountain, past and present • 100 XIV The paths of succession on E s t e l l a Mountain 102-103 XV S t a t i s t i c s r e l a t i n g t o wood production, Premier Ridge s i t e s . . . . •••105 v i i i Page XVI Statistics relating to wood production, Estella Mountain sites 107 XVII The aggregate annual understory productivity on Premier Ridge. 112 XVIII The aggregate annual understory productivity on Estella Mountain 116 i x LIST OP FIGURES Page 1. Map of the Premier Ridge study area 3 2. Map of the E s t e l l a Mountain study area 4 3. I l l u s t r a t i o n of the determination of c h a r a c t e r -i s t i c stand age l6 4. The Skookumchuck P r a i r i e , a n a t u r a l g r a s s l a n d . 24 5. The bluegrass-needlegrass p l o t , l o c a t e d near A l k a l i Lake ; 26 6. The bluegrass-needlegrass exclosure 27 7. The b i t t e r b r u s h s i t e 29 8 . A close-up of the b i t t e r b r u s h exclosure 30 9. The r e l i c t wheatgrass s i t e 32 10. Regeneration on the steep western aspects has been slow 34 11. The " t e r r a c e " area of Premier. Ridge 34 12. The young Douglas f i r . s i t e 35 13. The middle-aged Douglas f i r s i t e 37 14. The mature Douglas f i r s i t e 38 15. The young ponderosa pine s i t e . . 4-.1 16. The middle-aged ponderosa pine s i t e 44 17. A close-up of the middle-aged ponderosa pine s i t e 44 18. The climax ponderosa pine stand 45 19. The lodgepole pine stand on Premier Ridge 46 20. The regenerating Douglas f i r stand on E s t e l l a Mountain , 48 X Page 21 . The l a r c h stand 50 22. The lodgepole pine stand on E s t e l l a Mountain 51 23. The s e r a i fescue s i t e 53 24. The s e r a i wheatgrass s i t e 55 25. The abundance of s e v e r a l species of grasses on Premier Ridge as Influenced by c h a r a c t e r i s t i c stand age and f o r e s t canopy. 58 26. The abundance of s e v e r a l species of forbs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age 6l 27. The abundance of s e v e r a l species of forbs on Premier Ridge as i n f l u e n c e d by f o r e s t canopy. 62 28. The abundance of timber m i l k vetch and BaIsam-mo r h i z a sa.gittata on Premier Ridge as i n f l u e n c e d by f o r e s t canopy 63 29. The abundance of forbs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy 64 30. The abundance of dwarf shrubs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy 65 31 . The abundance of s e v e r a l species of grasses on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy 68 32. The abundance of forbs on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy ' • 72 33. The p r o d u c t i v i t y of grass on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy 74 The p r o d u c t i v i t y of grass on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The annual p r o d u c t i v i t y of dwarf shrubs on Premier Ridge as Influenced by c h a r a c t e r i s t i c stand age and f o r e s t canopy... The annual p r o d u c t i v i t y of bearberry on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The annual p r o d u c t i v i t y of b i t t e r b r u s h (twigs a n d j t h e i r leaves o n l y ) on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The annual p r o d u c t i v i t y of s o a p o l a l l i e (twigs and leaves) as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The p r o d u c t i v i t y of grasses on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. The p r o d u c t i v i t y of forbs on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The p r o d u c t i v i t y of dwarf shrubs on E s t e l l a Mountain a.s i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The annual p r o d u c t i v i t y of bearberry on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy The annual p r o d u c t i v i t y of s o a p o l a l l i e (twigs and leaves) as i n f l u e n c e d by c h a r a c t e r i s t i c stand :age and f o r e s t canopy, E s t e l l a s i t e s . . . I n e aggregate annual understory p r o d u c t i v i t y of Premier Ridge as i n f l u e n c e d by f o r e s t canopy. x i i Page 4 5 . The aggregate annual understory p r o d u c t i v i t y of Premier Ridge as i n f l u e n c e d by c h a r a c t e r -i s t i c stand age......... I l l 4 6 . The aggregate annual understory p r o d u c t i v i t y of E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age 11.4 4 7 . The aggregate annual understory p r o d u c t i v i t y of E s t e l l a Mountain as i n f l u e n c e d by f o r e s t canopy 1 1 5 x i v (A.e.- -*.v\v) ACKNOWLEDGEMENTS I would l i k e to thank Dr. V. C. Brink f o r h i s cont i n u i n g encouragement and t h o u g h t f u l guidance. Dr. Bri n k , Dr. P. J . Bandy and Dr. I . McTaggart Cowan v i s i t e d the study area and made many h e l p f u l suggestions. Valuable c r i t i c i s m was provided by other members of my committee, i n c l u d i n g Dr. W. D. K i t t s and Dr. L. M. L a v k u l i c h . Ray Demarchi and s t a f f of the Cranbrook o f f i c e of the P i s h and W i l d l i f e Branch a s s i s t e d t h i s p r o j e c t i n many ways; with t h e i r cooperation and that of the B. C. Forest S e r v i c e , the p r o j e c t went smoothly. The F i s h and W i l d l i f e Branch supported the f i e l d work i n the summers of 1968 and 1969 and t h e i r f i n a n c i a l a s s i s t a n c e was g r e a t l y appreciated. Mr. Rick Howie served as f i e l d a s s i s t a n t i n the summer of 1969 and h i s help was much appreciated. The measure of cooperation which was achieved w i t h the B.' C. Forest S e r v i c e , the B. C. F i s h and W i l d l i f e Branch and the l o c a l ranchers and c i t i z e n s was most g r a t i f y i n g . 1 INTRODUCTION Recent changes i n the populations of deer, elk and bighorn sheep i n the East Kootenay region have been l i n k e d to changes i n the v e g e t a t i o n of the c r i t i c a l w i n t e r ranges, brought about by l o g g i n g , burning and g r a z i n g by domestic animals. Widespread logging and burning of the montane f o r e s t s on the f l o o r of the southern Rocky Mountain Trench at the turn of the century removed almost a l l the mature f o r e s t s at low e l e v a t i o n s . The removal of the f o r e s t o v e r s t o r y I n i t i a t e d the development of s e r a i communities dominated by grasses, forbs and shrubs; the r e s u l t was an increase i n forage f o r ungulates. Small l o c a l populations of the large ungulates, e l k , bighorn sheep, mule deer and w h i t e - t a i l e d deer, p r e v i o u s l y considered not to be abundant, responded to t h i s expanding food supply by i n c r e a s i n g t h e i r d i s t r i b u t i o n and numbers. E a r l y s e t t l e r s i n the area took advantage of t h i s young s e r a i v e g e t a t i o n to r a i s e l i v e s t o c k . Since 1 9 3 0 f o r e s t f i r e s have been uncommon i n the southern Rocky Mountain Trench, and f o r e s t regeneration on the logged and burned areas has been r a p i d . Heavy s t o c k i n g r a t e s of domestic c a t t l e on those acres considered as c r i t i -c a l w i n t e r ranges f o r w i l d ungulates i s t a x i n g the e x i s t i n g range resource. A recent d i e - o f f i n Rocky Mountain bighorn 2 sheep has focused a t t e n t i o n on the problem, r e s u l t i n g i n the i n i t i a t i o n of range and animal-oriented research to examine the problem and suggest ways of preventing i t s recurrence. This study was i n i t i a t e d to determine: 1. The path and r a t e s of succession of the vegetat i o n . -^ 'g? > « ; ^ ^ 2. The e f f e c t of t r e e regeneration on the f l o r i s t i c composition of the understory. 3. The e f f e c t of f o r e s t regeneration on the annual understory p r o d u c t i v i t y . 4. The i n f l u e n c e of the current g r a z i n g p r a c t i c e s on the open s e r a i rangelands. The winter range s e l e c t e d f o r i n t e n s i v e study was Premier Ridge and adjacent E s t e l l a Mountain. A s e r i e s of exclosure p l o t s were e s t a b l i s h e d under the v a r i o u s types of secondary and climax f o r e s t s which e x i s t i n the area. Three p l o t s were e s t a b l i s h e d on open communities which have f a i l e d to regenerate to f o r e s t a f t e r logging which occurred about 1910. One p l o t on a n a t u r a l g r a s s l a n d , l o c a t e d near the study area,.was included i n the study f o r comparative purposes. A. Area D e s c r i p t i o n and H i s t o r y The southern Rocky Mountain Trench i n the east Kootenay region l i e s i n the southeast corner of B r i t i s h Columbia, bounded by the A l b e r t a border on the east, the Key to the s i t e s on Premier Ridge. 1 Mature Douglas f i r 2 Young Douglas f i r 3 B i t t e r b r u s h (Purshia) unforested 4 Poa - S t i p a unforested 5 Middle-aged ponderosa pine 6 Bluebunch wheatgrass unforested 7 Young ponderosa pine 8 Middle-aged Douglas f i r 9 Climax ponderosa pine Key to the s i t e s 1 Regenerating Douglas f i r 2 Larch 3 S e r a i fescue 4 Lodgepole Pine 5 ' S e r a i bluebunch wheatgrass 4 SCALE 150,000 Estella Mountain e '~ Montana border on the south and the P u r e e l l Mountains on the west. The northern boundary of the "southern trench" i s l o c a t e d i n the v i c i n i t y of Canal F l a t s , B r i t i s h Columbia. S o i l surveys and g e o l o g i c a l data f o r the area have been recorded by K e l l e y and Sprout ( 1956) and G. G. Runka ( 1 9 7 0 ) . The h i s t o r y of the East Kootenay region centres a.bout the e x p l o i t a t i o n of i t s n a t u r a l resources, f u r s , minerals and a r a b l e lands. Before the advent of white man, Indians grazed horses on the scanty n a t u r a l grasslands which e x i s t e d on the trench f l o o r , ( K e l l e y and Sprout 1 9 5 6). E a r l y explorers i n 1807 noted that the Kootenai Indians were "a s c r u f f y l o t " but that they possessed e x c e p t i o n a l l y f i n e horses. These explorers a l s o noted the absence of b i g game i n the area, s t a t i n g that food was d i f f i c u l t to o b t a i n . Another f a c t which f u r t h e r r e v e a l s the s c a r c i t y of large ungulates i s that the Kootenai Indians were o b l i g e d to make two annual forays through the Crowsnest Pass i n t o the p l a i n s to hunt b i s o n . These animals were probably t h e i r only s t a b l e meat source f o r much of the year. In the e a r l y l 8 0 0's the f u r trade was a c t i v e f o r about 50 years, g i v i n g way to a gold rush on the Wildhorse R i v e r (then c a l l e d the Stud Horse R i v e r ) i n 1 8 6 3 . The demand f o r meat i n the mining camps probably exerted moderate pressur 6 on the r e l a t i v e l y s m a ll populations of w i l d ungulates which e x i s t e d i n the area at that time. C a t t l e were few i n the area u n t i l 1890 at which time s e v e r a l ranchers had developed herds of 200 to 300 head ( K e l l e y and Sprout 1 9 5 6 ) . E a r l y logging records have proven d i f f i c u l t to obtain f o r t h i s area. Apparently the e a r l i e s t m i l l s opened about. 1 8 8 4 , and by 1910 r a i l w a y logging was being p r a c t i c e d on the trench f l o o r . Slash f i r e s and a c c i d e n t a l f i r e s were common f o l l o w i n g logging. V i r t u a l l y a l l of the bottom lands of the trench f l o o r were f i r e d one or more times. The o r i g i n a l f o r e s t cover of the trench f l o o r was predominately a mature Montane Forest of ponderosa pine (Pinus ponderosa) and Douglas f i r (Pseudotsuga m e n z i e s i i v a r . glauca) o c c u r r i n g i n mixed stands w i t h o c c a s i o n a l pure stands of e i t h e r s p e c i e s . Black cottonwood (Populus  t r i c h o c a r p a ) a.nd Englemann spruce (Picea engelmanni) were common i n moist draws and along r i v e r channels. On the eastern w a l l of the trenc h , Douglas f i r p r e s e n t l y predominates; ponderosa pine i s more abundant. on the d r i e r east w a l l and trench f l o o r , o c c u r r i n g to a . • maximum e l e v a t i o n of 4 , 0 0 0 f t . Above t h i s e l e v a t i o n , Englemann spruce d i s p l a c e s Douglas f i r on the more moist north and northeast aspects. Western l a r c h ( L a r i x o c c i -d e n t a l ! s ) i s a r u d e r a l and i s common i n moist l o c a t i o n s . At a l l e l e v a t i o n s , north and northeast slopes are more 7 h e a v i l y timbered than t h e i r south and southwest counter-p a r t s . Lodgepole pine (Pinus c o n t o r t a v a r . l a t i f o l i a ) occurs s p o r a d i c a l l y , at a l l e l e v a t i o n s , u s u a l l y f o l l o w i n g f i r e . N a t u r a l grasslands are r e s t r i c t e d to dry benches of the trench f l o o r where Bluebunch wheatgrass (Agropyron  spicatum) and rough fescue (Festuca s c a b r e l l a ) were once the dominant species. However, heavy g r a z i n g pressure by domestic stock reduced or e l i m i n a t e d the bunchgrasses r e -p l a c i n g them w i t h sparce stands of p e r e n n i a l Poa and S t i p a , and annual grasses and weeds which p r e s e n t l y c o n s t i t u t e the main cover. E r r a t i c logging and burning on the trench f l o o r has l e f t a complex v e g e t a t i o n a l p a t t e r n of secondary f o r e s t s w i t h o c c a s i o n a l open s e r a i and n a t u r a l grasslands. On l i m i t e d acreages, u s u a l l y on south or soxathwest slopes, p r e v i o u s l y logged areas have not yet regenerated to f o r e s t cover. A combination of environmental f a c t o r s coupled w i t h heavy gr a z i n g pressure by both w i l d and domestic ungulates may be r e t a r d i n g f o r e s t regeneration. Many of these open areas are regarded as c r i t i c a l w i n t e r ranges f o r w i l d ungulates. An a c t i v e C h r i s t m a s t r e e i n d u s t r y i s p r a c t i c e d i n s e v e r a l areas; the trees are cut so they w i l l regrow. V i r t u a l l y a l l of the open and semi-open rangeland 8 of the trench f l o o r i s grazed by c a t t l e and many of these areas support some w i n t e r i n g n a t i v e ungulates from December to May. In ea.rly s p r i n g , a r a b l e lands are a l s o used by n a t i v e game animals. B. Climate The c l i m a t e of the southern Rocky Mountain Trench i s sub-humid w i t h an annual p r e c i p i t a t i o n of 14 - 20 inches per year. Much of t h i s f a l l s as snow during the winter months from November to February, although a secondary peak i n p r e c i p i t a t i o n occurs i n June. The s p r i n g thaw u s u a l l y provides adequate s o i l moisture f o r growth, being r e i n f o r c e d by the June r a i n s ( K e l l e y and Sprout 1 9 5 6). The d i f f e r e n c e between good and poor growing years i s r e l a t e d to the June p r e c i p i t a t i o n . During the summer of 1 9 6 9 , when most of the p r o d u c t i v i t y samples were taken, the June p r e c i p i t a t i o n was remarkably high (about 7 " ) . Hence the values f o r pro-duction should be considered as maximal r a t h e r than average. Summer convective and orographic p r e c i p i t a t i o n may extend the growing season on the trench f l o o r . High summer temperatures on the trench f l o o r , p a r t i c u l a r l y on south and southwest slopes where ambient a i r temperatures exceeding 1 0 0 ° F are sometimes recorded, s e v e r e l y l i m i t the e f f e c t i v e -ness of summer p r e c i p i t a t i o n . The east w a l l of the trench f l o o r above 4 , 0 0 0 f t . i s c o o l e r and r e c e i v e s more frequent 9 r a i n f a l l throughout the year from p r e v a i l i n g w e s t e r l y weather systems. K e l l e y and Sprout ( 1956) reported that the growing season on the trench f l o o r was approximately 180 days, from A p r i l 15 to e a r l y October. At higher e l e v a t i o n s the growing season i s correspondingly s h o r t e r , but c o o l e r summer temperatures permit almost continuous growth. On the trench f l o o r dormancy i n grasses and forbs occurs about the second week i n J u l y . C. The Problem Following extensive logging and burning on the trench f l o o r e a r l y i n the tw e n t i e t h century, b i g game populations increased, responding to the increased fora,ge made a v a i l a b l e by man's a l t e r a t i o n of the h a b i t a t . A second s e r i e s of f i r e s e a r l y i n the t h i r d decade destroyed many of the young f o r e s t s which had begun to r e - e s t a b l i s h on the trench f l o o r . Ranchers took advantage of t h i s new range resource by i n c r e a s i n g the s t o c k i n g r a t e s of domestic c a t t l e and horses. The numbers of la r g e w i l d ungulates remains higher than those recorded p r e v i o u s l y , however a gradual d e c l i n e has been noted s i n c e 19^5* as trees once again begin to be predominant over the trench f l o o r . The i n s t i t u t i o n of very e f f e c t i v e f i r e p r o t e c t i o n f o r the young f o r e s t s has r e s u l t e d i n a c o n t i n u a l s h r i n k i n g of open range acreage. Stocking 10 rates i n most s e c t i o n s of the trench have not been adjusted to a l l o w f o r t h i s decrease In range acreage; consequently, fewer and fewer acres are forced to support the same numbers of stock. Thus, overgrazing may be more severe w i t h each passing year. Small h i l l s or anomalies on the trench f l o o r have been used as t r a d i t i o n a l w i n t e r ranges by l o c a l populations of mule deer, w h i t e - t a i l e d deer, Rocky Mountain bighorn sheep and e l k . With the exception of w h i t e - t a i l e d deer, these animals summer at high e l e v a t i o n s i n the Rocky Mountains, using vast areas which i n the foreseeable f u t u r e w i l l not be g r e a t l y modified by man. The continued s u r v i v a l of these populations i s dependent upon c r i t i c a l w i n t e r and e a r l y s p r i n g ranges which dot the trench f l o o r . The u t i l i z a t i o n of these ranges c r i t i c a l f o r w i l d l i f e i n w i n t e r , by c a t t l e during the summer reduces the forage a v a i l a b l e f o r w i l d l i f e . s In order to obta i n some measure of the e f f e c t s of f o r e s t regeneration and succession on the species composition and p r o d u c t i v i t y of the understory community, t h i s study was es t a b l i s h e d under the j o i n t cooperation of the U n i v e r s i t y of B r i t i s h Columbia and the B r i t i s h Columbia Pish and W i l d l i f e Branch. 11 I I METHODS AND MATERIALS A. C r i t e r i a f o r S i t e S e l e c t i o n A reconnaissance survey of the Premier Ridge area and the surrounding trench f l o o r revealed that g r a z i n g was concentrated p r i m a r i l y on south and southwestern slopes and the adjacent f l a t open areas of the trench f l o o r . The veg e t a t i o n of the r i d g e appears to be s i m i l a r to the communities common to the f l o o r of the trench. The vege-t a t i o n of the adjacent east w a l l of the trench ( E s t e l l a Mountain) i s d i s t i n c t l y d i f f e r e n t , r e f l e c t i n g increased p r e c i p i t a t i o n and c o o l e r temperatures a s s o c i a t e d w i t h higher e l e v a t i o n s . Aspect has a profound e f f e c t on micro-cl i m a t e i n t h i s area, p a r t i c u l a r l y on e f f e c t i v e s o i l moisture; consequently, the s i t e s s e l e c t e d f o r study were r e s t r i c t e d to south and southwestern aspects. The f o r e s t cover of Premier Ridge i s composed of ponderosa pine and Douglas f i r ; lodgepole pine and l e s s commonly l a r c h , u s u a l l y f o l l o w f i r e . On northeast slopes, ponderosa pine i s absent but western l a r c h i s common i n moist draws. The mature montane f o r e s t stands of a few decades ago were l a r g e l y c l e a r c u t , l e a v i n g a . s e r i e s of secondary stands of va r y i n g ages and species composition. Douglas f i r and ponderosa pine were the most abundant and wide-spread s p e c i e s , consequently young, mature, and climax 12 stands of these species were sought f o r i n t e n s i v e study-on Premier Ridge. One lodgepole stand on Premier was a l s o s e l e c t e d and three open s e r a i range s i t e s were i n c l u d e d , representing areas which were once timbered and logged, but which f a i l e d to regenerate to t r e e s . One s i t e e sta-b l i s h e d by the B r i t i s h Columbia Forest S e r v i c e , Grazing D i v i s i o n , on the Skookumchuck P r a i r i e , a n a t u r a l grass-land, was included i n t h i s study f o r comparative purposes. F i v e s i t e s were s e l e c t e d on nearby E s t e l l a Mountain to measure the e f f e c t of increased e l e v a t i o n and p r e c i p i t a t i o n on succession and p r o d u c t i v i t y . Two of these s i t e s were logged i n the 1 9 5 0 ' s ; one i s a l a r c h stand and the other a Douglas f i r s i t e . The remaining three s i t e s on E s t e l l a are s i t u a t e d on a 1 9 3 ^ burn which swept the mountain from bottom to top. A lodgepole s i t e was esta- . b l i s h e d on an area which has been dominated by lodgepole r pine s i n c e the f i r e . An open fescue and an open bunchgrass s i t e were e s t a b l i s h e d on two areas which have remained un-f o r e s t e d s i n c e the f i r e . At each s i t e a 3 0 ' x 3 0 ' exclosure, eight f e e t high was constructed, excluding a l l ungulates from the p l o t . W i t h i n t h i s area eighteen meter square quadrats were layed out i n a fixed, p a t t e r n , from which the p r o d u c t i v i t y c l i p s were taken.. A 100 foot square macroplot, c o n c e n t r i c with the exclosure, was l a i d out at each s i t e . (This area 13 was not fenced i n any way.) Trees and la r g e shrubs were sampled from the macroplot; grasses, forbs and dwarf shrubs were sampled from the exclosure. C o n s t r u c t i o n of a l l exclosures was completed by August 1 9 6 8 . Two s i t e s were added i n e a r l y May 1 9 6 9 . These were an open bluegrass-needlegrass s i t e and an open b i t t e r b r u s h s i t e , both located on Premier Ridge. In two cases, the open bluebunch wheatgrass s i t e : on Premier Ridge and the open fescue s i t e on E s t e l l a , the e n t i r e macroplot was fenced. B. S i t e D e s c r i p t i o n Techniques The aspect and percent slope of each p l o t was • recorded i n the f o l l o w i n g manner. The percent slope was obtained with a Suunto Level by s i g h t i n g from the centre of the upper macroplot boundary to the centre of the lower macroplot boundary. (The instrument s c a l e reads percent slope d i r e c t l y . ) The aspect was measured by compass, con-s i d e r i n g the macroplot as a plane sur f a c e ; the d i r e c t i o n , i n degrees from magnetic n o r t h , i n which the plane was t i l t e d was considered to be the aspect. A map was drawn f o r each macroplot showing the l o c a t i o n of each t r e e , stump and l a r g e shrub, i n c l u d i n g a reference number under which the v a r i o u s parameters des-c r i b i n g that p l a n t were l i s t e d . A canopy map of the f o r e s t overstory was made f o r the macroplot using a 3 meter square 14 g r i d of 100 p o i n t s . At each poi n t on the g r i d a. v e r t i c a l s i g h t i n g was taken w i t h a Gimball s i g h t (Dodd 1 9 6 9 ) . Only-l i v i n g branches, trunks and limbs were recorded as canopy " h i t s " . Open sky or dead branches were recorded as misses. For each s i g h t i n g the h i t or miss was recorded f o r a. sm a l l dot on the m i r r o r of the instrument. Since the g r i d has 100 p o i n t s , the number of h i t s recorded i s the percent f o r e s t canopy cover, at eye l e v e l ( 5 1 ) - This method should not be confused w i t h a s i m i l a r method which records the canopy cover of each t r e e on an i n d i v i d u a l b a s i s . Since canopies overlap, values above 1 0 0 $ are common, but t h i s study considered the canopy as a u n i t , and using t h i s system, values higher than 80$> are uncommon. Each t r e e mapped i n the macroplot was c l a s s i f i e d by s p e c i e s , age, diameter breast height (DBH), diameter at stump height (DIH) and t o t a l h e ight. The l o c a t i o n , age at c u t t i n g time, species and c o n d i t i o n of a l l stumps i n the macroplot was recorded. S o a p o l a l l i e (Sherpherdia canadensis ) pl a n t s i n each macroplot were mapped and ranked according to t h e i r f o l i a r diameter and hei g h t . B i t t e r b r u s h (Purshia tridentata.) p l a n t proved to be too numerous to measure i n d i v i d u a l l y ; t h e r e f o r e a. 10 rank s c a l e of s i z e was used to record t h i s species i n the macroplot. 15 The understory v e g e t a t i o n (dwarf shrubs, forbs and grasses) at each s i t e was described using Daubenmire's l/10th meter frame method (Daubenmire, 1959). F o r t y frames were counted i n each macroplot, 20 on each side of the ex-c l o s u r e , p a r a l l e l i n g the contour. C. Determination of C h a r a c t e r i s t i c Stand Age The assessment of age of a stand of tr e e s or an open s e r a i community i s not a simple procedure. While the trees at a p a r t i c u l a r s i t e may be, i n the main, 50 years o l d , the disturbance which l e d to the establishment of the stand i n the f i r s t p l a c e , may have occurred many years p r e v i o u s l y . For example, open s e r a i communities on the southwest s i d e of Premier Ridge are the r e s u l t of logging which occurred about 1910, but they have not yet regen-erated to f o r e s t . Thus, wh i l e t h e i r s u c c e s s i o n a l age i s about 60 years, t h e i r age i n terms of f o r e s t succession i s zero. The terms s u c c e s s i o n a l age, c h a r a c t e r i s t i c stand-age and premodal age, are used Interchangeably i n t h i s t e x t , and r e f e r t o the e a r l i e s t p o i n t of I n f l e c t i o n of the peak on a graph, which represents the m a j o r i t y of the tre e s In the stand. The use of a premodal age permits p r e d i c t i o n s ; to be made from the time a major environmental disturbance occurred. Figure 3 shows a graph of the trees found i n one Figure 3- I l l u s t r a t i o n of the determination of c h a r a c t e r i s t i c stand age. The trees are grouped into age classes (each containing 5 year classes) and plotted on a graph. The point of i n f l e c t i o n of that peak which represents tne Dulk of the trees i s taken as the date at which the stand was i n i t i a t e d . The character-i s t i c stand age of this example i s 65 years. 1969 Age Class 1904 17 macroplot, i l l u s t r a t i n g the determination of character-i s t i c stand age. The trees were grouped Into 5 year i n t e r -v a l s or c l a s s e s and p l o t t e d against time. Most of the trees are represented by a l a r g e peak, and the e a r l i e s t point of i n f l e c t i o n of t h i s peak i s the " c h a r a c t e r i s t i c age" of the s i t e . D. Annual P r o d u c t i v i t y Assessments (Net p r o d u c t i v i t y of B l i s s and Westlake) To f a c i l i t a t e p r o d u c t i v i t y assessments, the v e g e t a t i o n at each s i t e was d i v i d e d i n t o s i x c a t e g o r i e s ; ( l ) t r e e s , ( 2 ) l a r g e shrubs, ( 3 ) dwarf shrubs, ( 4 ) f o r b s , ( 5 ) grasses, ( 6 ) bearberry. ( l ) Trees The annual p r o d u c t i v i t y of the t r e e s was derived i n crude terms by c a l c u l a t i n g the standing volume of timber i n each macroplot and d i v i d i n g t h i s f i g u r e by the c h a r a c t e r -i s t i c stand age. The volume of each t r e e was c a l c u l a t e d using the formula (Smith and Breadon- 1 9 6 4 ) 1. V = a + bH where V = volume i n f t . 3 B a = species c o e f f i c e n t b = 1 B = b a s a l area at- DBH H = height of t r e e The volume increment per year was c a l c u l a t e d using the formula 2 . p s jr ]/ where *P = increment/year ~ T ~ * A = c h a r a c t e r i s t i c stand age 18 (2) B i t t e r b r u s h and S o a p o i a l l i e The annual p r o d u c t i v i t y of b i t t e r b r u s h and s o a p o i a l l i e was determined by subsampling r e p r e s e n t a t i v e p l a n t s which had been p r e v i o u s l y mapped i n the macroplot and assigned a s i z e category. A s i m i l a r method was used by Quadvleig ( 1 9 6 8 ) . Two r e p r e s e n t a t i v e s i z e s o a p o i a l l i e p l a n t s were s e l e c t e d at random (from a l i s t ranked according to s i z e ) and cut down at ground l e v e l . The current year's twigs and a l l the leaves on the pl a n t were removed and stored In paper bags. The remaining p o r t i o n of the p l a n t (wood o l d e r than 1 y r . ) was a i r - d r i e d on the open range f o r 2 weeks. At t h i s time, the pl a n t was weighed and a s e c t i o n was cut from the base to age the p l a n t . These s e c t i o n s were sanded smooth and examined under a low power microscope; l i g h t o i l was used to f a c i l i t a t e the counting of annual r i n g s . . To determine the s i z e of each p l a n t , the f o l l o w -ing formula was used Crude Volume = 3.l4 x r 2 x h where r = rad i u s of p l a n t a.t ground l e v e l h = t o t a l height of pl a n t The crude volume f o r a l l the s o a p o i a l l i e p l a n t s i n each macroplot was determined. The annual p r o d u c t i v i t y (annual twigs plus a l l leaves on the p l a n t ) was determined 19 by oven-drying the current twigs and leaves at 50° C to constant weight. For each p l a n t , and f o r each s i t e , an index of the weight of twigs and leaves produced annually per cubic foot (of crude volume) was c a l c u l a t e d . The t o t a l crude volume m u l t i p l i e d by the average weight of annual twigs and leaves y i e l d e d a t o t a l annual p r o d u c t i v i t y f i g u r e f o r s o a p o i a l l i e at that s i t e . A l l p l a n t s were sampled i n August 1 9 6 9 when twig elongation had ceased. The b i t t e r b r u s h p l a n t s i n the macroplots proved to be too numerous to count, hence a s i z e c l a s s system was adopted, employing a 10 rank s c a l e . Representative, randomly s e l e c t e d p l a n t s i n each macroplot were cut at ground l e v e l and t h e i r current twigs and attached leaves were removed. The leaves on the remaining p o r t i o n of the-plant (secondary wood) were not c o l l e c t e d . The p l a n t s were then d r i e d on the open range f o r two weeks. At the end of t h i s p e r i o d the o l d wood was weighed and a s e c t i o n was removed from the base of the p l a n t f o r aging. The t o t a l macroplot p r o d u c t i v i t y of b i t t e r b r u s h was determined by m u l t i p l y i n g the average annual weight of oven d r i e d twigs and leaves f o r each s i z e c l a s s by the number of p l a n t s i n that s i z e c l a s s . In summary, these t o t a l s produced a t o t a l weight f o r that s i t e . A l l b i t t e r b r u s h p l a n t s were sampled i n August when annual twig growth had ceased. B i t t e r b r u s h and s o a p o i a l l i e were not sampled from 20 w i t h i n the exclosure; s i z e removal of such l a r g e components of the ve g e t a t i o n could s e v e r e l y a l t e r any changes i n the community afforded hy t h e i r p r o t e c t i o n from g r a z i n g . (3) Grasses, forbs and dwarf shrubs The grasses, forbs and.dwarf shrubs were c l i p p e d from one meter quadrats which l a y w i t h i n the exclosure fence. The quadrats were p r e - c l i p p e d i n the l a t e f a l l of 1968 and were c l i p p e d three times during 1 9 6 9 ; these c l i p p i n g periods were June 2 - 7 , J u l y 23 - 27 and October 4 - 9 . The June c l i p occurred during the growing season, the J u l y c l i p f o l l owed mid-summer dormancy of the grasses, and the October c l i p preceded permanent winter snows. At each c l i p p i n g date, 6 meter quadrats were c l i p p e d at each s i t e ; the three com-ponents of the ve g e t a t i o n were c o l l e c t e d i n separate bags. These samples were a i r - d r i e d i n the f i e l d and then oven-dried i n a f o r c e d - a i r d r i e r at 5 0 ° C u n t i l constant weight was achieved. Unless otherwise noted, the y i e l d f i g u r e s represent the J u l y c l i p when they p e r t a i n to grass, forb or dwarf shrub m a t e r i a l . ( 4 ) Bearberry Bearberry or k i n n i k i n n i k (Arctostaphylos u v a - u r s i ) was sampled on 4 to 6 one-meter square quadrats outside the exclosure i n the month of August. A l l the bearberry i n the 21 quadrat was removed; when a runner crossed the quadrat frame i t was cut at that p o i n t . New growth was separated from o l d e r growth. These samples were oven-dried at 5 0 ° C to a constant weight. The f l o r i s t i c and p r o d u c t i v i t y data have been presented i n graphic form i n t h i s t e x t . The curves on these graphs are r e p r e s e n t a t i v e of the trend of the data, and should not be i n t e r p r e t e d as a l e a s t squares f i t . 22 I I I OBSERVATIONS AND RESULTS A. S i t e D e s c r i p t i o n Sixteen non-randomly lo c a t e d s i t e s were s e l e c t e d f o r i n t e n s i v e study. These included one n a t u r a l g r a s s l a n d , nine f o r e s t e d areas and f i v e areas which once were f o r e s t e d hut which have f a i l e d to regenerate f o l l o w i n g logging and/or burning. Most of the s i t e s (ten) were lo c a t e d on Premier Ridge on communities used by w i l d and domestic ungulates. The three open s i t e s (unforested) on Premier Ridge i n -cluded areas l i g h t l y , moderately and h e a v i l y used by domestic c a t t l e . H i s t o r i c a l l y , these s i t e s compare to the r e s t of the s i t e s on Premier. Gen e r a l l y the s i t e s are named a f t e r a conspicuous element of t h e i r v e g e t a t i o n or by t h e i r l o c a t i o n . Timbered s i t e s u s u a l l y bear the name and some rough i n d i -c a t i o n of the ma t u r i t y of t h e i r dominant t r e e species. Open s e r a i s i t e s (being t r e e l e s s ) are named a f t e r a shrub or grass species. The s i t e s are not d i r e c t l y comparable to those on Premier Ridge because they r e f l e c t the e f f e c t of e l e v a t i o n . Since w i l d ungulates may forage on the east w a l l of the trench below 6,000 f t . i n m i l d winters and during l a t e s p r i n g and e a r l y f a l l , a knowledge of the species composition and pro-d u c t i v i t y of these areas, e s p e c i a l l y f o l l o w i n g f i r e s and logging, i s p e r t i n e n t . 23 1 . Skookumchuck P r a i r i e N a t u r a l Grassland This s i t e Is the only n a t u r a l grassland p l o t In the s e r i e s . I t Is r e p r e s e n t a t i v e of the l i m i t e d and s c a t t e r e d acreage of n a t u r a l grasslands which dot the f l o o r of the Rocky Mountain Trench. These grasslands have "been used h e a v i l y by domestic stock and very l i t t l e of the p r i s t i n e v e g e t a t i o n remains. The data used i n t h i s study were derived from an exclosure b u i l t i n 1952 on the Skookumchuck P r a i r i e by the B r i t i s h Columbia Forest S e r v i c e . The n a t u r a l vege-t a t i o n has responded w e l l to the 17 years of p r o t e c t i o n from g r a z i n g and i s now f a i r l y r e p r e s e n t a t i v e of the climax grass-lands of the area. The community dominants are bluebunch wheatgrass and rough fescue which occupy 63% and 9% of the cover, r e s p e c t i v e l y . Junegrass ( K o e l e r i a c r i s t a t a ) covers 8% of the ground surface. Bluegrass (Poa spp. ) and needle-grass ( S t i p a spp.) were dominants on the s i t e p r i o r to the c o n s t r u c t i o n of the exclosure. Both genera have been a l l but e l i m i n a t e d from the exclosure. No shrubs or trees are present but ponderosa pine occurs nearby on the g r a v e l l y , very porous s o i l which c h a r a c t e r i z e s the Skookumchuck P r a i r i e . The t o t a l ground cover by grasses was 80$. Forbs occupied a t o t a l cover of 6%, phlox (Phlox ca e s p i t o s a ) was the p r i n c i p a l . f o r b {3%) but nine other species were recorded. An unprotected area adjacent to but outside the 2 4 Figure 4. The Skookumchuck P r a i r i e , a n a t u r a l grassland. 25 exclosure fence was a l s o sampled. Junegrass was the most abundant species occupying a cover of 16$. Needlegrass and bluegrass occupied 12% and 3% r e s p e c t i v e l y . The once domi-nant bluebunch wheatgrass cover was 10% and rough fescue was present i n t r a c e amounts. The t o t a l ground cover by grasses outside the p l o t was k0%. Forbs were common, eleven species being recorded, pussytoes (Antennaria p a r i i f l o r a ) and f l e a -bane (Erigeron l i n e a r i s ) were the most abundant species having ground covers of 2% and 3% r e s p e c t i v e l y . The Skookumchuck P r a i r i e p l o t i s shown In Figure 4. 2. Premier Ridge Non-forested S i t e s Mature climax montane f o r e s t p r e v i o u s l y occupied the three non-forested s i t e s on Premier Ridge. Douglas f i r was the p r i n c i p a l species and stumps of t h i s species w i t h bark attached, remained i n the area, i n v a r i o u s stages of decay. The removal of the f o r e s t and the t r e e canopy has given r i s e to widespread open, s e r a i , non-forested communities. P r e v i o u s l y more widespread, these communities are l a r g e l y now confined to the south and southwestern slopes of Premier Ridge. a- Bluegrass-Needlegrass S i t e This s i t e i s subjected to the heaviest g r a z i n g pressure (by domestic stock) of a l l the s i t e s on Premier Ridge. Adjacent to A l k a l i Lake, one of the main water sources f o r domestic stock, t h i s community i s h e a v i l y grazed by c a t t l e from May 1 to the l a t e f a l l . Kentucky bluegrass F i g u r e 5. The b l u e g r a s s - n e e d l e g r a s s p l o t , l o c a t e d near A l k a l i Lake. Note the stumps o f the p r e v i o u s f o r e s t and t h e "weedy" i n d i c a t o r s p e c i e s o f o v e r g r a z i n g i n t h e f o r e g r o u n d . Figure 6 . The bluegrass-needlegrass exclosure. Notice the reduced carryover outside the fence. 28 (Poa p r a t e n s l s ) and Canada bluegrass (Poa compressa) were abundant at t h i s s i t e , forming a t o t a l of 2 2 $ of the herb-aceous cover. Junegrass and downy brome (Bromus tectorum) were a l s o common covering 11$ and 8 $ of the ground surface r e s p e c t i v e l y . Bluebunch wheatgrass (cover 2 $ ) and needle-grass (cover 3 $ ) were present i n l e s s e r q u a n t i t i e s . Seven-teen species of forbs were recorded at t h i s ,sit.e. No species achieved a ground cover g r e a t e r than 2 $ . Shrubs were preva-l e n t , b i t t e r b r u s h being the most abundant w i t h a ground coyer of 1 7 $ . Saskatoon (Amelanchier a l n l f o l l a ) covered 4 $ w h i l e f l a t - t o p s p i r a e a (Spiraea l u c i d a ) covered 2 $ . Bearberry was abundant, covering 12$ of the ground sur f a c e . b. B i t t e r b r u s h S i t e .; :-This area i s the second i n the s e r i e s of unforested open s i t e s . Located about 3 / 8 mi., from A l k a l i Lake, i t r e -ceives moderate to heavy g r a z i n g pressure from c a t t l e . Kentucky bluegrass and Canada bluegrass are the most abundant grasses, both species a c h i e v i n g a cover of 1 7 $ . Downy brome was a l s o common, covering l 4 $ . Junegrass was l e s s common, covering 2 $ , w h i l e bluebrunch wheatgrass and needlegrass were present i n t r a c e amounts (cover l e s s than 1 $ ) . Twenty-two species of forbs were recorded. Balsam root (Balsamorhlza s a g i t t a t a ) covered 1 0 $ , Oyster p l a n t (Tragopogon dubius) covered 1 $ , showy a s t e r (Aster consplcuus 2 9 Figure 7. The b i t t e r b r u s h s i t e . The exclosure can be seen i n the background. F i g u r e 8 . A closeup of the b i t t e r b r u s h exclosure. 31 covered 4 $ . The t o t a l cover by forbs at t h i s s i t e was 3 4 $ . Shrubs were very abundant, b i t t e r b r u s h dominated the s i t e w i t h a ground cover of 2 5 $ , saskatoon covered 2 $ , w h i l e s p i r a e a covered 2 $ . Bearberry was present i n t r a c e amounts. c. The R e l i c t Bluebunch Wheatgrass S i t e This s i t e i s the t h i r d i n the open unforested s e r i e s . S i t u a t e d on a steep slope about two miles from the nearest water source, t h i s area r e c e i v e s almost no grazi n g from domestic stock. I t Is w e l l used by w i n t e r i n g bighorn sheep and mule deer. Use by elk i s l i g h t . Bluebunch wheatgrass dominates the s i t e , covering 5 1 $ of the ground s u r f a c e . Junegrass i s a l s o common, covering 9 $ , a t r a c e of downy brome was recorded. T o t a l cover by grass species was 6 0 $ . The most abundant forb was balsam root with a cover of 3 $ . Pour other forbs were r e -corded i n tra c e amounts. T o t a l cover by forbs was 4 $ . Shrubs were not abundant at this s i t e . B i t t e r b r u s h covered 4 $ , saskatoon occupied 2 $ and rose (Rosa spp. ) covered 3 $ . T o t a l cover by shrubs was 9 $ . 3 . Premier Ridge Forested S i t e a. The Young Douglas F i r S i t e This p l o t i s s i t u a t e d i n a stand of mature timber which was s e l e c t i v e l y logged about 1 9 1 0 . Some trees were cut. i n recent years. The stand p r e s e n t l y i s composed l a r g e l y of young f i r trees from 3 to 15 f t . i n h e i g h t , hut 32 Figure 9'. The r e l i c t bluebunch-wheatgrass s i t e . Steepness of slope has allowed these ridges to escape the heavy gra z i n g which i s c h a r a c t e r i s t i c of the lower areas i n t h i s photograph. 33 a few mature t r e e s remain on the s i t e . While the area Is probably not r e p r e s e n t a t i v e of a c l e a r - c u t logging p r a c t i c e , no s i t e s were found which contained very young f i r stands. Most of the mature Douglas f i r was removed from the r i d g e e a r l y i n the twentieth century and regeneration e i t h e r commenced immediately or has been " s t a l l e d " by c l i m a t i c and g r a z i n g f a c t o r s . The young f i r stand contained 1 9 3 0 stems per acre and had a f o r e s t canopy cover of 2 0 $ . The pre-modal age was 22 years. A few l a r c h and lodgepole pine were present at t h i s s i t e , but ponderosa pine was absent. The grass component of the understory was l a r g e l y composed of pinegrass (Calamagrostls  rub esc ens) which had a ground cover of 4 2 $ . Rough fescue, was a l s o abundant at 11$ and junegrass covered only 1 , 2 $ . The t o t a l cover by grass species was 5 4 $ . F i f t e e n species of forbs were recorded, the most abundant being w i l d straw-b e r r y ( F r a g a r i a glauca) and white pussytoes. The t o t a l cover-by forbs was 1 5 $ . Shrubs were common, saskatoon covered 7 $ , s p i r a e a 4 $ , b i t t e r b r u s h , s o a p a l a l l i e and rose together covered 1 $ . Bearberry was very common, occupying 17$ and making up one h a l f of the t o t a l shrub cover of 33$. b. The Middle-aged Douglas F i r S i t e This s i t e had a. f o r e s t canopy cover of 5 6 $ and a pre-modal age of 55 years. However, logging during the summer of 1969 removed s e v e r a l mature trees from t h i s s i t e . This had Figure 10. Regeneration on the steep western aspects has been slow. This s i t e was cut about 1 9 1 5 -Figure 11. The " t e r r a c e " area.of Premier Ridge. Note the r a p i d , widespread regeneration of young trees. Figure 1 2 . The young Douglas f i r s i t e . 36 l i t t l e e f f e c t on the y i e l d s recorded during t h i s study. There were 6 0 5 stems per acre at the s i t e , most of which were Douglas f i r , hut one l a r c h and s e v e r a l ponderosa pine t r e e s were a l s o present. Pinegrass dominated the sparse understory community present at t h i s s i t e , w i t h a ground cover of 2 9 $ . Bluebunch wheatgrass, junegrass and needlegra.ss were present In very s m a l l q u a n t i t i e s . No bluegrass species were present. The t o t a l ground cbver by grasses was 46$. F i f t e e n species of forbs were r e -corded, but they t o t a l l e d only 17$ ground cover. Penstemon (Penstemon spp.), w i l d strawberry, timber milk vetch (Astragalus miser var. s e r o t i n u s ) and yarrow ( A c h i l l e a  m i l l e f o l i u m ) were the most common. The r a p i d l y developing f o r e s t canopy was probably r e s p o n s i b l e f o r the dead and t h i n l y developed shrubs at t h i s s i t e . B i t t e r b r u s h covered only 3 $ , s p i r a e a 5 $ , saskatoon 7 $ and bearberry 2 $ . T o t a l shrub cover was 1 8 $ . c. The Mature Douglas F i r S i t e This was the only p l o t which was not e s t a b l i s h e d on a south or southwest slope. The only remaining stand of mature Douglas f i r on Premier Ridge i s located on the north-east slope of the r i d g e . Since t h i s aspect i s d i s t i n c t l y more humid than those on which the other p l o t s were l o c a t e d , r i g i d d i r e c t comparisons between them should not be made. Figure 1 3 . The middle-aged Douglas f i r s i t e . N o tice the dead shrubs i n the foreground. Figure 1 4 . The mature Douglas f i r s i t e . 39 The area s e l e c t e d f o r study has a pre-modal age of 95 years, and 331 stems per acre, w i t h a f o r e s t canopy cover of 73$. The only grass present was pinegrass which had a ground cover of 43$. S i x species of forbs were present i n t r a c e amounts. Spiraea was the most abundant shrub covering 26$ of the ground, Oregon grape (Mahonia repens) and rose were present i n t r a c e amounts. Moss covered 12$ of the ground surface. Scattered s o a p o i a l l i e p l a n t s occurred throughout the s i t e , u s u a l l y holes i n the f o r e s t canopy, d. Young Ponderosa Pine S i t e . This s i t e i s r e p r e s e n t a t i v e of those stands of t r e e s which have a r i s e n as a r e s u l t of the logging and f i r e s which removed the mature timber. This stand had 958 stems per acre and a f o r e s t canopy cover of 49$. The pre-modal age was 80 years. 1 While, the stand has more f i r . t r e e s than p i n e , the pines c u r r e n t l y dominate the f i r . The undercover was. sparse, w i t h pinegrass as the most abundant species covering 29$. Rough fescue covered 5$ and junegrass 1$ of the ground surface. The t o t a l cover by grass was 35$. Sixteen species of forbs covered a t o t a l of 10$ of the ground sur f a c e . Nodding onion ( A l l i u m cernuum), w i l d straw-b e r r y , balsam root and yarrow were a l l present, covering about 1$ of the ground. Shrubs were not abundant, t h e i r t o t a l cover was 12$. Saskatoon covered 4$ , b i t t e r b m s h 4$ and s p i r a e a 1$. Bearberry covered 2$. 4 0 e. Middle-aged Ponderosa Pine S i t e Thig s i t e I s s i t u a t e d on the top of a dry k n o l l near A l k a l i Lake. I t i s a v e r y uniform stand. There are no stumps sugge s t i n g the e x i s t e n c e o f an e a r l i e r f o r e s t . The pre-modal age was 100 y e a r s , and the f o r e s t canopy, cover, was 4 9 $ . There were 2 61 stems per a c r e . Pinegrass was the most abundant u n d e r s t o r y g r a s s c o v e r i n g 2 2 $ . Rough fes c u e and bluebunch wheatgrass are present with covers of 2 $ and 4$ r e s p e c t i v e l y . Trace amounts o f junegrass were a l s o r e corded. T h i r t e e n s p e c i e s of f o r b s covered a t o t a l o f 2 3 $ . Timber milk v e t c h was most abundant c o v e r i n g 14$. Shrubs, were common, but the p l a n t s -were t h i n and weakly developed. The t o t a l shrub cover was 3 2 $ , h a l f of t h i s being b e a r b e r r y ("17$), w h i l e saskatoon covered 11$ and b i t t e r b r u s h 4 $ ? f . Climax Ponderosa Pine S i t e A 2 8 0 year o l d stand of ponderosa pine was chosen to r e p r e s e n t the climax f o r e s t of the t r e n c h f l o o r . T h i s s i t e had a f o r e s t canopy cover of 3 8 $ w i t h 74 stems per a c r e , and appears t o have been r e l a t i v e l y u n a f f e c t e d by . major env i ro nm en t a 1 d i s t u r b a n c e s i n recent times. The p r i n c i p a l u n d e r s t o r y grass was p i n e g r a s s c o v e r i n g 18$ o f the s u r f a c e . Bluebunch wheatgrass covered 11$ and june-grass covered 5$. Rough fe s c u e covered 1$ and the t o t a l cover by g r a s s was 3 6 $ . T h i r t e e n s p e c i e s of f o r b s covered 2 1 $ o f the s u r f a c e . Balsam r o o t at 1 2 $ , and timber m i l k Figure 15. The young ponderosa pine s i t e . 42 vetch at 4 $ were the most prominent s p e c i e s . Shrubs were abundant under the r e l a t i v e l y open canopy of the climax f o r e s t , covering a t o t a l of 3 5 $ - K i n n i k i n n i k covered 1 7 $ , b i t t e r b r u s h 1 5 $ , saskatoon 4 $ and s p i r a e a covered 1 $ . g. The Lodgepole Pine Stand The lodgepole pine stand on Premier Ridge i s r e p r e s e n t a t i v e of r e l a t i v e l y 'uniform stands which occur on the study area. - These stands are the r e s u l t of f i r e s which followed l o g g i n g . The lodgepole s i t e on Premier i s located on a burn w i t h i n the climax ponderosa pine f o r e s t . Scattered trees from the o r i g i n a l f o r e s t s t i l l remain. The dense lodgepole s i t e had a canopy cover of 7 8 $ and a pre-modal age of 65 years. There were 3 , 4 5 9 stems per acre. Pinegrass was the main understory grass w i t h a canopy cover of 3 9 $ . Rough fescue had a cover of 2 $ . F i f t e e n species of forbs covered 1 5 $ . Pussytoes and w i l d straws berry.were the most common covering, 2 $ and 1$ r e s p e c t i v e l y . The shrub cover was 2 0 $ i n t o t a l , but appeared to be de-c l i n i n g as sparse or dead p l a n t s were common. K i n n i k i n n i k was abundant, covering 1 0 $ , saskatoon covered 7 $ and b i t t e r -brush 2 $ . 4 . The E s t e l l a Mountain F o r e s t e d . S i t e s The "Regenerating D o u g l a s . f i r " and the "Larch" s i t e s on E s t e l l a Mountain were s e l e c t i v e l y logged about 1 9 5 2 . These s i t e s are r e p r e s e n t a t i v e of the types of logging used i n the area and i t s subsequent e f f e c t s on the understory 43 community. The remaining three s i t e s , the s e r a i bluebunch wheatgrass, the s e r a i fescue and the lodgepole area, were e s t a b l i s h e d on a burn which occurred i n 193^- The two s e r a i s i t e s have f a i l e d to regenerate to t r e e s . The lodge-pole s i t e i s r e p r e s e n t a t i v e of the r e f o r e s t e d area which developed f o l l o w i n g the f i r e i n the o r i g i n a l stands which were Douglas f i r and whitebark pine (Plnus a l b i c a u l i s ) . Ponderosa pine i s n e a r l y absent from the w a l l s of the trench (above 4 , 0 0 0 f t . ) , Douglas f i r i s p r e v a l e n t , as i s l a r c h , : . and on the n o r t h and northeast slopes Englemann spruce i s very common. a. The Regenerating Douglas F i r S i t e The regenerating Douglas f i r s i t e at the 4 , 1 7 0 f t . e l e v a t i o n was thinned by s e l e c t i v e logging about 1 9 5 2 . S i t u a t e d on a bench w i t h g r a v e l l y , w e l l - d r a i n e d s o i l , t h i s s i t e has a pre-modal age of 17 years. However, o l d mature trees remain at the s i t e and comprise most of the present-day f o r e s t canopy cover of 3 5 $ . Stands which have been s e l e c t i v e l y logged are u s u a l l y d i f f i c u l t to age. Con-sequently, the age has been deri v e d from the time of the l a s t major environmental disturbance ( l o g g i n g , i n t h i s case). There i s no evidence to suggest that t h i s stand has been burned i n recent times. The stand d e n s i t y was 5 5 3 stems per acre and pinegrass was the most abundant understory grass covering 4 2 $ of the ground surface. Rough Figure 1 7 . A close-up of the middle-aged ponderosa pine s i t e . F i g u r e ] .8 . E s t e l l a Mountain as seen from ttee f l o o r o f the Rocky Mountain Trench. Figure 19. The lodgepole pine s i t e on Premier Ridge. Note the o l d ponderosa pine "veterans" which survived the f i r e which gave r i s e to the lodgepole stand In the background. 47 fescue was present i n t r a c e amounts, p o s s i b l y r e i n v a d i n g a f t e r the stand was thinned. T o t a l grass cover was 4 2 $ . Eleven species of forbs were recorded; heart-leaved a r n i c a (Arnica c o r d i f o l i a ) covered 8 $ and timber m i l k vetch covered 6 $ . The t o t a l cover by forbs was 2 2 $ . Shrubs formed a major p o r t i o n of the understory; bearberry covered l 8 $ , s p i r a e a 12$ and Rocky Mountain j u n i p e r (Juniperus scopuiorum) covered 8 $ . b. The Larch S i t e The l a r c h s i t e on E s t e l l a Mountain i s located i n a moist draw at the 4 , 2 2 0 f t . e l e v a t i o n . Logged In 1952 t h i s s i t e i s c u r r e n t l y dominated by l a r c h ; the understory i s a r a p i d l y developing stand of young Douglas f i r . The e x i s t i n g l a r c h trees are 6 0 to 70 f e e t high, have a f o r e s t canopy cover of 7 2 $ and a pre-modal age of 125 years. The grass understory i s dominated by pinegrass covering 5 2 $ . Ten species of forbs had a t o t a l cover of 2 6 $ . Heart-leaved a r n i c a covered 1 7 $ , w i l d strawberry 2 $ and bronze b e l l s or western stenanthium (Stenanthium o c c i d e n t a l e ) covered 2 $ . Shrubs were an important component of the understory covering 2 5 $ of the ground surface. Spiraea 12$ and twin flower (Llnnaca b o r e a l i s ) 3$ were the most common species. c. The Lodgepole S i t e The lodgepole s i t e on E s t e l l a . i s r e p r e s e n t a t i v e F i g u r e 20. The r e g e n e r a t i n g Douglas f i r s t a n d on E s t e l l 8 Mounts i n . 4 9 of t h i c k stands of lodgepole pine which followed the f i r e of 1 9 3 4 . The e l e v a t i o n of the s i t e i s 5 , 9 8 0 f t , and the pre-modal age i s 35 years. The f o r e s t canopy cover was 7 1 $ i n t h i s stand which had 1 , 6 3 4 stems per acre. Pinegrass was the only grass species present, having a ground cover of 2 9 $ . Twelve species of forbs covered 3 7 $ . Most abundant were heart-leaved a r n i c a covering 7 $ , a s t e r (Aster consplcuus) covering 1 2 $ . Shrubs occupied 2 3 $ of the ground cover; s p i r a e a and s o a p o l a l l i e were most common wit h covers of 7 $ each. Bearberry, rose and twin flower were a l s o present. 5 . E s t e l l a Mountain Non-forested S i t e s a. S e r a i Fescue S i t e The s e r a i fescue s i t e on E s t e l l a i s lo c a t e d at the 5 , 9 6 0 f t e l e v a t i o n . Standing and f a l l e n t rees of the burned whitebark pine f o r e s t remain at the s i t e . Lodgepole pine has f a i l e d to e s t a b l i s h but s e v e r a l whitebark pine seedlings were found i n the macroplot. The pre-modal age of t h i s s i t e i s zero, i n terms of r e f o r e s t a t i o n , however a burn occurred 35 years ago. The grass community at t h i s s i t e i s c u r r e n t l y dominated by rough fescue which has a cover of 4 l $ . Pinegrass i s a l s o present, probably as a r e s u l t of the previous f o r e s t , covering 7 $ . Canada bluegrass and an u n i d e n t i f i e d Festuca spp. were present i n t r a c e F i g u r e 22. The lodgepole pine stand on E s t e l l a Mountain. The opening i n the foreground i s the r e s u l t of the road cut. 52 amounts. The t o t a l cover by grass was 48$. Porbs were abundant; seventeen species had a t o t a l cover of 4l$. Common species were white penstemon w i t h 16$ cover, yarrow 6$ and locoweed (Oxytropis campestris) which covered 3$ of the ground surface. Shrubs were not abundant w i t h a t o t a l cover of 11$; bearberry covering 5$ , was most common, whi l e s p i r a e a , Rosa spp. and w i l l o w ( S a l i x spp.) were a l s o present. d. The S e r a i Bluebunch Wheatgrass S i t e The. s e r a i bluebunch wheatgrass s i t e on E s t e l l a . i s l o c a t e d on a grassy f i n g e r of v e g e t a t i o n i n the lodge-pole pine f o r e s t at an e l e v a t i o n of 6,200 f t . Tree r e -generation d i d not f o l l o w the burn of 1934 and the s i t e i s dominated by rough fescue but i s unique because wheatgrass species occupy 6$ cover. No bluebunch wheatgrass was found on the lower e l e v a t i o n fescue s i t e , but i t occurs on the same burn at an e l e v a t i o n of 4,500 f t . Bluegrass covered 4$ at t h i s s i t e ; the t o t a l cover by grasses was 33$. Nineteen species of forbs were recorded, t o t a l l i n g 17$ cover. Common species were stonecrop (Sedum spp.) 3$ cover, yarrow 2$ cover and narrow-leaved parsley. (Lomatium tr i t e r n a t u r n ) covered 3$. No shrubs were found on the s i t e , but s c a t t e r e d clumps of bearberry were F i g u r e 2 3 . The s e r a i f e s c u e s i t e . N o t i c e t h e burned stumps o f the w h i t e - b a r k p i n e f o r e s t which e x i s t e d p r i o r t o t h e 1934 f i r e . T h i s photo-graph was t a k e n " d o w n h i l l " l o o k i n g toward th e f l o o r o f the t r e n c h . 54 observed i n the v i c i n i t y . B. F l o r i s t i c Dynamics 1. The Premier Ridge S i t e s . The three unforested s i t e s on Premier were esta-b l i s h e d on two v e g e t a t i o n types, the r e l i c t bluebunch wheatgrass grassland and the b l u e g r a s s - b i t t e r b r u s h community. The wheatgrass grassland was probably i n i t i a t e d by the r e -moval of the timber from the already f a i r l y open f o r e s t , of which bluebunch wheatgrass would have been an important member of the understory community. The removal of the f o r e s t has allowed t h i s s i t e t o s h i f t dynamically toward the f l o r i s t i c c h a r a c t e r i s t i c s of the n a t u r a l g r a s s l a n d In the area. The understory of the bluegrass-needlegrass s i t e and the b i t t e r b r u s h s i t e probably d i d not contain any blue-grass species at the time of logging. However, the r e l a t i v e p r o x i m i t y of these s i t e s (and most of the bluegrass-b i t t e r b r u s h community) to water and t h e i r r e l a t i v e f l a t n e s s , probably subjected them to heavy constant g r a z i n g f o l l o w i n g logging and the f i r e s which swept the area. Consequently, Canada bluegrass and Kentucky bluegrass were able to domi-nate the s i t e r a t h e r than bluebunch wheatgrass which would r e q u i r e more time and l i g h t e r g r a z i n g pressure f o r sub- • s t a n t i a l development. 5 5 F i g u r e 2 4 . The s e r a i bluebunch wheatgrass s i t e . The burned f o r e s t was one o f w h i t e - b a r k p i n e . The l i v i n g t r e e s i n the p i c t u r e a r e l o d g e p o l e p i n e . N o t i c e t h e e f f e c t o f a s p e c t on the p a t t e r n of the r e -g e n e r a t i o n . 56 Rough fescue may have been a member of the f o r e s t understory, however i t s extreme s e n s i t i v i t y to heavy g r a z i n g has e f f e c t i v e l y removed i t from the unforested s i t e s which were stud i e d on Premier Ridge. The r e l i c t bluebunch wheat-grass s i t e on Premier i s the s i t e most r e p r e s e n t a t i v e of the nature of the succession when unaffected by heavy gr a z i n g by domestic, stock. Consequently, t h i s s i t e was se l e c t e d to represent the open unforested areas of the r i d g e . The place, of the b l u e g r a s s - b i t t e r b r u s h community and i t s r e l a t i o n s h i p to the f l p r i s t i c dynamics w i l l be discussed i n a l a t e r s e c t i o n on the e f f e c t of g r a z i n g on community composition and p r o d u c t i v i t y . a. Grasses The r e l i c t bluebunch wheatgrass s i t e i s character-i s t i c of unforested communities which developed f o l l o w i n g logging and burning under a r e l a t i v e l y moderate gr a z i n g regime. Bluebunch wheatgrass dominates the s i t e and a ground cover of about 5 0 $ i s common. Junegrass i s the only other common grass. As r e f o r e s t a t i o n commences an immediate re d u c t i o n i n the bianchgrasses i s noted; these species r e -main uncommon or may completely disappear from the under-s t o r y , u s u a l l y reappearing i n climax f o r e s t s as the f o r e s t canopy opens. The l e v e l of abundance achieved i n these climax stands I R about 20$ of that achieved on the un-57 f o r e s t e d s i t e s . Junegrass a l s o becomes l e s s abundant as the f o r e s t develops reappearing i n the climax f o r e s t community, where i t may achieve 5 0 $ of i t s former abund-ance. Pinegrass i s very uncommon on the open s i t e s , however i t increases r a p i d l y as f o r e s t regeneration commences. On moist s i t e s pinegrass may reach a ground cover of 4 0 $ ' or more i n s p i t e of a heavy f o r e s t canopy. The t o t a l ground cover by a l l species of grasses decreases w i t h i n c r e a s i n g stand age. Tables I and I I and Figure 25 d e p i c t the trends of grass ground cover as c h a r a c t e r i s t i c stand age and f o r e s t canopy cover change, b. Forbs The c h a r a c t e r i s t i c stand age and the f o r e s t canopy cover seemed to have no pronounced e f f e c t on the total,abundance of forbs ( F i g s . 26, 27, 28 and 29). I n d i -v i d u a l species show strong preference f o r c e r t a i n f o r e s t canopy types. Yarrow, sedge (Carex spp.), pussytoes, nodding onion and w i l d strawberry are sciophytes ( F i g s . 26 and 27). Balsam root i s a he l i o p h y t e w h i l e timber milk vetch seems to be a sciophyte ( F i g . 28). The number of forb species present at the v a r i o u s s i t e s was r e l a t i v e l y constant, except f o r the r e l i c t bluebunch wheatgrass s i t e which had only 5 species of f o r b s . In the climax f o r e s t forbs were most common, comprising 21$ of the ground cover. Figure 25. The abundance of s e v e r a l species of grasses on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. » Rough fescue m i D B Pinegrass itmsm v Bluebunch wheatgrass 50 40 30 20 10 v o i \ a 10 20 30 4o 50 60 70 8o 90 no 130 280 C h a r a c t e r i s t i c Stand Age CD |> O o 50 40 30 ^ 20 10 Forest canopy % 59 Table I The i n f l u e n c e of c h a r a c t e r i s t i c stand age on the species dynamics of the understory grass species expressed as percent ground cover. Forest stand age Grass sp. 0 22 55 65 80 "95 100 280 Bluebunch wheatgrass 51 . '•••3 . 4 ... 11 Rough fescue 11 ; 8 • 2 5 2 1 Junegrass ". • 9 1 . i 1 T 5. Needlegrass T ' 5 Pinegrass 42 29 39 29 43 22 18 T o t a l ground cover by grasses 60 54 46 4l 35 43 28 35 Table I I The i n f l u e n c e ground cover of f o r e s t canopy cover on of the grass component of the percent the understory % Forest canopy cover Grass sp. 0 26 38 49 49 56 71 78 Bluebunch wheatgrass 51 11 4 3 Rough fescue 11 1 5 2 8 2 Junegrass 9 1 5 1 T 1 Needlegrass T 5 Pinegrass 42 18 29 22 29 43 39 T o t a l ground cover by grass spp. 60 54 36 35 28 46 43 4l 6o c. Shrubs The abundance of shrubs on the unforested s i t e s was v a r i a b l e , and d i r e c t l y r e l a t e d to g r a z i n g pressure. Figure 30 and Table I I I d e p i c t the r e l a t i o n s h i p between c h a r a c t e r i s t i c stand age and shrub abundance. Shrubs i n -creased s l i g h t l y as f o r e s t regeneration began, dropped o f f i n dense, middle-aged stands and began to reappear i n mature and climax f o r e s t s . The e f f e c t of f o r e s t canopy on the percent ground cover of shrubs i s shown i n Table I I I and Figure 30. Shrubs were v a r i a b l e i n cover on the unforested s i t e s and Increased s l i g h t l y i n the middle canopy ranges, but beyond a 50$ canopy c l o s u r e shrubs decreased s h a r p l y , except on the northeast slope (mature f i r s i t e , 73$ canopy). B i t t e r b r u s h decreased r a p i d l y w i t h f o r e s t r e -generation and reappeared i n the climax f o r e s t . Bearberry, u s u a l l y present In very s m a l l amounts In unforested s i t e s , increased sharply i n middle-aged stands and i n the middle canopy ranges. 2. E s t e l l a Mountain a. Grasses The trends e s t a b l i s h e d f o r the Premier Ridge data appear to hold f o r the E s t e l l a s i t e s . Rough fescue f r e -quently replaces bluebunch wheatgrass as the dominant bunchgrass on unforested s i t e s . 61 Figure 26. The abundance of s e v e r a l species of forbs on Premier Ridge, as i n f l u e n c e d by c h a r a c t e r i s t i c stand age. o denotes abundance i n n a t u r a l grassland community CD > o o 4 3 2 1 4 3 2 1 4 3 2 1 4 3 2 1 4 3 2 1 4 3 2 1 Yarrow Wild Onion Hyi».i».MIwi. I IUIHI. . I I I1IH . . .UI..IIII^... • "I'm1,; I mn nii; • • Wild Strawberry / Penstemori 1—m—1 -i 1 i 1 r 1—8—J—rV » *i 0 20 4o 60 80 100 120 280 C h a r a c t e r i s t i c Stand Age 62 Figure 2 7 . The abundance of s e v e r a l species of forbs on Premier Ridge as i n f l u e n c e d by f o r e s t canopy. o denotes l e v e l i n n a t u r a l grassland community Forest Canopy % 63 Figure 2 8 . The abundance of timber m i l k vetch and balsam-root on Premier Ridge as i n f l u e n c e d by f o r e s t canopy. o denotes l e v e l i n n a t u r a l g r a s s l a n d community CD > o o l4 12 10 8 6 4 2 12 10 8 6 4 2 Timber m i l k vetch T T i I J i 1 r 20 30 4o 50 6o 70. 8o 90 Forest Canopy % 64 CD > O o Figure 2 9 . The abundance of forbs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. o denotes l e v e l i n n a t u r a l grassland community 35 30 25 20 15 10 5 T — I — r — i — i i a — i — n — r o 20 4o 6o 8o IOO r r 120 I 280 C h a r a c t e r i s t i c Stand A g e 65 Figure 3 0 . . The abundance of dwarf shrubs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. 0 > o o 50 4o 30 10 10 T 0 20 " T " 40 i \ 60 T 80 T—r .100 n—1—T/ ~T~ 120 140 280 C h a r a c t e r i s t i c Stand Age Forest Canopy % Table I I I The abundance of shrubs on the Premier Ridge s i t e s , i n r e l a t i o n to c h a r a c t e r i s t i c stand age and f o r e s t canopy. C h a r a c t e r i s t i c Stand Age 0 0 0 22 55 65 8 0 95 100 2 8 0 Forest Canopy % 0 0 0 2b 5b 78 49 72 49 3b1 S p i r e a 1 .5 2 . 3 4 . 4 4 . 8 1 . 4 2 6 . 3 1 . 2 0 . 6 Rose 3 . 0 2 . 5 1 . 0 1 . 2 0 . 1 0 . 9 Oregon Grape 0 . 9 Saskatoon 2 . 0 2 . 4 3 . 8 7 . 1 7 - 0 7 - 3 4 . 3 1 1 . 2 3 . 7 Bearberry 0 . 5 1 1 . 6 1 6 . 9 20 1 0 . 1 2 . 2 1 7 . 1 l 6 . 5 B i t t e r b r u s h 3 . 6 2 5 . 0 1 6 . 6 1 . 3 2 . 5 2 . 2 3 - 7 0 . 4 1 5 . 0 S o a p o l a l l i e 1 . 0 1 . 6 T o t a l % cover 8 . 6 2 9 . 4 4 l . 8 3 4 . 7 1 7 . 5 2 0 . 7 1 1 . 6 2 8 . 1 3 1 - 5 3 5 . 8 by shrubs 67 Figure 31 shows the e f f e c t of c h a r a c t e r i s t i c stand age on the species abundance of grasses. On most unforested areas, a bunchgrass dominates the community ( 2 0 - k0% cover). Pinegrass i s present i n t r a c e amounts on these open areas and increases i n abundance as f o r e s t regeneration commences. The bunchgrasses are reduced i n abundance or disappear completely. Pinegrass may be the s o l e grass present i n mature f o r e s t stands. The e f f e c t of f o r e s t canopy on grass abundance on E s t e l l a Mountain i s shown i n FIgtire 3 1 . The pa.ttern i s s i m i l a r to the one described f o r c h a r a c t e r i s t i c stand age. The time r e q u i r e d f o r the f o r e s t to develop on E s t e l l a , i s c o n s i d e r a b l y l e s s than i s r e q u i r e d on Premier Ridge. b. Forbs The abundance of forbs on E s t e l l a Mountain, as assessed by ground cover, f o l l o w s a p a t t e r n s i m i l a r to that found on Premier Ridge. C h a r a c t e r i s t i c stand age and f o r e s t canopy have l i t t l e e f f e c t on t o t a l forb abundance ( F i g . 3 2 ) . T h i r t y - n i n e species of forbs were recorded at the f i v e E s t e l l a s i t e s . The highest s i t e , 6 , 2 0 0 f t . a l s o had the greatest number of forb s p e c i e s , 1 9 . There was not a s u f f i c i e n t numberof s i t e s on E s t e l l a Mountain to a s c e r t a i n which forbs were he l i o p h y t e s and which were sciophytes. c. Shrubs There was no d e f i n i t e trend i n the shrub data when 68 Figure.31. The abundance of s e v e r a l species of grasses on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. Rough fescue B B Pinegrass v Bluebunch wheatgrass 6 9 Table IV The abundance of s e v e r a l species of grasses as measured by percent ground cover on E s t e l l a Mountain. Tabulated w i t h reference to c h a r a c t e r i s t i c stand age and f o r e s t canopy. C h a r a c t e r i s t i c Stand Age 0 0 25 35 .125. Forest Canopy 0 0 35 7 1 7 2 Rough fescue Bluebunch wheatgrass Pinegrass Bluegrass T o t a l % cover by grasses 4 0 . 9 2 2 . 3 0 . 5 6 . 2 6 . 9 4 1 . 7 2 9 . 0 5 1 . 7 0 . 1 4 . 4 4 8 . 3 3 2 . 9 4 2 . 2 2 9 . 0 5 1 . 7 70 Table V. The abundance of forbs as measured by percent ground cover on E s t e l l a Mountain, recorded re-.---. l a t i v e to c h a r a c t e r i s t i c stand age and f o r e s t . canopy. : C h a r a c t e r i s t i c Stand Age . 0 / 0 25 35 125 -Forest Canopy 0 0 35 71 72 Pussytoes 1 T Fireweed T 1 . 7 A r n i c a c o r d i f o l i a T 8 . 1 6 . 7 1 6 . 8 Sedges T T 1 . 9 3 . 0 Mountain death 3 . 2 P y r o l a secunda 1 . 8 Hedysarum sulphur esc ens . 3 . 3 L O 1 . 6 1 . 7 Yarrow 5 . 7 1 . 6 T T Penstemon procerus 1 5 . 6 1 . 2 Locoweed 3 . 4 T Timber m i l k vetch T 6 . 2 T Wild strawberry T 1 . 9 Bronze b e l l s 1 . 6 Twinflower 2 . 7 Stonecrop 3 . 7 Nodding onion 1.1 Narrow leaved p a r s l e y 2 . 5 Mountain p h a c e l i a 1 .5 Aster conspicuus 8 . 3 2 . 0 1 2 . 0 1 . 9 Number of other species present i n t r a c e 1 . 0 ) abundance 7 10 =4 2 5 . Ground cover by forbs 4 1 . 8 1 8 . 9 2 2 . 4 3 6 . 5 3 8 . 2 7 1 compared w i t h c h a r a c t e r i s t i c stand age and f o r e s t canopy. B i t t e r b r u s h i s not found on the E s t e l l a s i t e s , being r e -s t r i c t e d to e l e v a t i o n s below 4 , 0 0 0 f t . In g e n e r a l , t o t a l shrub abundance was about the same magnitude as that found on Premier Ridge. The abundance of shrubs on E s t e l l a Mountain i s l i s t e d i n Table VI. Table V I . S t a t i s t i c s f o r Shrub Abundance on E s t e l l a Mountain C h a r a c t e r i s t i c Stand Age 0 0 Years 25 35 125 Forest Canopy 0 0 35 71 72 Spiraea Rose Bearberry S o a p a l a l l i e Unknown sp. T o t a l shrub cover 2 . 7 -1 . 8 8 . 7 5 . 2 -1 2 . 0 6 . 9 0 . 1 1 . 0 1 8 . 1 4 . 1 0 . 1 6 . 9 9 . 7 8 . 7 3 0 . 3 1 8 . 9 1 1 . 7 1 .5 7 . 0 2 0 . 2 C. P r o d u c t i v i t y 1. Premier Ridge a. Grass P r o d u c t i v i t y The t o t a l p r o d u c t i v i t y of grass was highest on the open s i t e s and lowest on those s i t e s with dense canopies and r a p i d l y growing t r e e s . The e f f e c t which f o r e s t r e -generation has on grass production i s evident i n Figure 3 3 . 72 Figure 3 2 . The abundance of forbs on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. > O O 50 40 30 20 10 J 0 T — r 20 u i i — T ~ T — r 4o 6o 8o C h a r a c t e r i s t i c Stand Age 280 Forest Canopy % 73 Average production of grasses on the three open s i t e s was 53 gm/m2 ( 4 7 2 Tb/AC). Twenty years a f t e r the i n i t i a l stages of f o r e s t r e g eneration, grass p r o d u c t i v i t y dropped to 6 2 $ of i t s former l e v e l . F i f t y - f i v e years f o l l o w i n g f o r e s t regeneration only 2 5 $ of the open area p r o d u c t i v i t y i s achieved by grasses. " Production of grass remains low, u n t i l the stand begins t o , t h i n . As the f o r e s t ages, grass pro-duction r i s e s s l i g h t l y . In these climax f o r e s t stands about 4 0 $ of the grass production of open areas may be a t t a i n e d . A s i m i l a r trend i s noted when f o r e s t canopy cover i s used as a v a r i a b l e i n measuring grass p r o d u c t i v i t y ( F i g - 3 3 ) . At a f o r e s t canopy of 2 6 $ , grass p r o d u c t i v i t y dropped to 5 1 $ of the open areas and at a f o r e s t canopy of 5 0 $ production dropped to 3 8 $ . Species changes occur w i t h i n c r e a s i n g shade and must t h e r e f o r e be regarded as a con-founding f a c t o r . b. Forb P r o d u c t i v i t y Forb abundance i s o f t e n reduced i n climax grass-lands and g r e a t l y increases i n secondary g r a z i n g successions. Despite d i f f i c u l t i e s i n a n a l y s i n g forb performace and occurr-ence i n f l o r i s t i c s t u d i e s , t h e i r importance to grazers warrants s p e c i a l c a t e g o r i z a t i o n . Figure 34 r e f l e c t s the v a r i a b i l i t y i n forb abund-ance and production on the open areas. Average production 7h F i g u r e 33. The p r o d u c t i v i t y of grass on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. Forest Canopy % 75 f o r the three s i t e s was 15 gm/m2 ( l 4 7 Ib/AC.). S i x t y - f i v e years a f t e r the onset of f o r e s t r e -generation, forb abundance dropped to 17$ of i t s previous l e v e l . Beyond eighty years, forb production increases and i n climax stands (over 2 5 0 years) may a c t u a l l y exceed the production achieved on the open areas. There i s l i t t l e change i n forb production u n t i l the f o r e s t canopy exceeds 5 0 $ cover ( F i g . 3 4 ) . Beyond t h i s p o i n t , p r o d u c t i v i t y decreases although an o c c a s i o n a l s i t e may y i e l d abundance of f o r b s . Tne l a r g e d e v i a t i o n from the trend i n F i g . 1 5 , at 3 8 $ , represents the climax ponderosa pine stand. c. Dwarf Shrub P r o d u c t i v i t y No meaningful trends are d i s c e r n a b l e i n the dwarf shrub data f o r Premier Ridge. Changes i n p r o d u c t i v i t y are masked by changes i n species composition and s o i l moisture at each s i t e . The r e l a t i v e c o n t r i b u t i o n of these p l a n t s i s s m a l l , t h e i r production i s shown i n Figure 3 5 . d. Bearberry Produc t i v i t y The e f f e c t of c h a r a c t e r i s t i c stand age on the annual p r o d u c t i v i t y of bearberry i s shown i n Figure 3 6 . Production on open areas i s r e l a t i v e l y low, but increases r a p i d l y as f o r e s t regeneration commences. Beyond an age of 50 years, most stands have become s u f f i c i e n t l y dense to cause some redu c t i o n i n bearberry production. As 76 Figure 34. The p r o d u c t i v i t y of forbs on Premier RIdg as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. 7 0 9 * i — I — \ — j — t — \ \ \ u—T°T—i—i—i—i / — r 0 20 4 0 6 0 8 0 100 120 2 8 0 C h a r a c t e r i s t i c Stand Age 7 0 ^ C\J 6 0 Forest Canopy % 77 n a t u r a l t h i n n i n g commences at ages beyond 100 years, bearberry production increases and i s f r e q u e n t l y a major component of the understory v e g e t a t i o n of the climax community. Production of bearberry i s low on the open s i t e s , r i s e s u n t i l canopy covers of l e s s than 5 0 $ are reached then d e c l i n e s under canopies g r e a t e r than 5 0 $ ( P i g . 3 5 ) . e. B i t t e r b r u s h P r o d u c t i v i t y The open s i t e s a n nually produce very l a r g e q u a n t i t i e s of b i t t e r b r u s h . Some v a r i a b i l i t y among these open s i t e s r e s u l t s from d i f f e r e n c e s i n g r a z i n g i n t e n s i t y . The onset of f o r e s t regeneration s e v e r e l y depresses b i t t e r -brush production. Twenty-five years a f t e r regeneration had commenced b i t t e r b r u s h production was l e s s than 1/3 of i t s former l e v e l . F i f t y years l a t e r , production was n e g l i g i b l e and t h i s l e v e l w i l l be maintained u n t i l the f o r e s t climax i s reached In which b i t t e r b r u s h u s u a l l y becomes more abundant. Production i n the climax f o r e s t compares favour-a b l y w i t h average open s i t e s . These trends are shown i n Figure 3 7 . The r e l a t i o n s h i p between b i t t e r b r u s h production and f o r e s t canopy i s shown i n Figure 3 7 - Production, which i s high on the open s i t e s d e c l i n e s s t e a d i l y , except f o r an abrupt r e d u c t i o n at 3 8 $ which represents the climax stand 78 F i g u r e 3 5 . The annual p r o d u c t i v i t y of dwarf shrubs on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. Forest Canopy % 79 3 6 . The annual p r o d u c t i v i t y of bearberry on Premier Ridge as i n f l u e n c e d by character-i s t i c stand age and f o r e s t canopy. Forest Canopy % 8 0 of pine and f i r . Beyond a f o r e s t canopy of 5 0 $ , b i t t e r -brush production i s very low, w h i l e a . f o r e s t canopy of 2 6 $ i s s u f f i c i e n t to lower production to 3 9 $ of i t s former l e v e l . ' f. S o a p o i a l l i e P r o d u c t i v i t y The production of s o a p o i a l l i e v a r i e s l i t t l e with s e r a i stage and changes r e l a t i v e l y l i t t l e with the one ex-ception that on c e r t a i n s i t e s I t i s e x c e p t i o n a l l y pro-d u c t i v e and abundant j u s t before and during the stages of f o r e s t regeneration. S o a p o i a l l i e p r e f e r s moist s i t e s with s o i l moisture w e l l maintained through the growing season, and i s not common i n pure stands of ponderosa pine. Figure 38 shows the p r o d u c t i v i t y of s o a p o i a l l i e under v a r i o u s f o r e s t canopies. Since t h i s species f r e q u e n t l y grows under major breaks or openings i n the canopy, an average canopy cover may not be the most e f f e c t i v e way t o measureits s i t e preference. Canopy covers of 2 0 $ to 4-0$ e x h i b i t the highest annual twig production on an area b a s i s . 2 . E s t e l l a Mountain a. Grass P r o d u c t i v i t y The production of grass on E s t e l l a Mountain followed a p a t t e r n si.milar to Premier Ridge, but was somewhat higher than that of the lower area. The e f f e c t of c h a r a c t e r i s t i c stand age on grass production i s shown In Figure 3 9 . Pro-• 8 i ;.. The annual p r o d u c t i v i t y of b i t t e r b r u s h (twigs and t h e i r leaves o n l y ) on Premier Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. I i I I I I l 2 0 4 0 6 0 C h a r a c t e r i s t i c Stand Age I I I I I / 8 0 100 120 2 8 0 1—7 1 0 2 0 Forest Canopy % t e x t f o r explanation of t h i s p o i n t 82 Figure 3 8 . The annual p r o d u c t i v i t y of s o a p o i a l l i e (twigs and leaves) as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. Premier Ridge s i t e s . Forest Canopy % 83 duction i s high on open s i t e s , 54 gm/m2 (529 l h / a c . ) and de c l i n e s r a p i d l y as f o r e s t regeneration commences. A f t e r 35 years grass production i s 28$ of that achieved on open areas. Production increases as stands mature and reaches 62$ of the open area, production i n 125 years. Grass production d e c l i n e s s t e a d i l y with i n c r e a s -ing f o r e s t canopy. The low l e v e l s of production which were recorded f o r Premier Ridge under dense f o r e s t canopies do not seem to occur on E s t e l l a Mountain ( F i g . 39). b. Forb P r o d u c t i v i t y The forb production of the open areas on E s t e l l a Mountain i s r e l a t i v e l y h igh, being composed of fewer species than i s c h a r a c t e r i s t i c of the lower, more h e a v i l y grazed ranges. Mean y i e l d s on open s i t e s was 18 gm/m (l60 l b / a c . ) . They d e c l i n e s t e a d i l y as f o r e s t canopy and c h a r a c t e r i s t i c stand age increase. T h i r t y - t h r e e years a f t e r the onset of fo r e s t regeneration the forb y i e l d i s reduced by 50$. The fo r e s t canopy a s s o c i a t e d w i t h such. a. d e c l i n e i s about 70$. Forb production i s shown In Figure 40. c. Dwarf Shrub P r o d u c t i v i t y The r e l a t i o n s h i p between c h a r a c t e r i s t i c stand age and dwarf shriib p r o d u c t i v i t y i s shown i n Figure 41. Y i e l d s vary from 3 to 12 gm/m2 (27 to 167 lb/ac.) on theopen s i t e s and remain at these l e v e l s f o r the f i r s t 30 to 40 years of tre e regeneration. Y i e l d s i n o l d e r stands are very low, 8 4 Figure 3 9 . The p r o d u c t i v i t y of grasses on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. Forest Canopy % 85 2 gm/m (17 l b / a c ) . There was no d i s c e r n a b l e r e l a t i o n s h i p between dwarf shrub production and f o r e s t canopy, as shown i n Figure 4 l . d. Bearberry P r o d u c t i v i t y Bearberry was very abundant on one s i t e on E s t e l l a Mountain. At a l l other s i t e s I t y i e l d e d l e s s than 5 gm/m2 ( 4 4 . 5 l b / a c ) . There*are not s u f f i c i e n t observations to a s c e r t a i n whether t h i s i s a common phenomenon. P r o d u c t i v i t y appears to be depressed i n open areas and under very dense f o r e s t canopies, being somewhat higher at intermediate cano-p i e s , as shown i n Figure 4 2 . e. B i t t e r b r u s h P r o d u c t i v i t y B i t t e r b r u s h does not occur on E s t e l l a Mountain at the e l e v a t i o n s at which the p l o t s were e s t a b l i s h e d . f. Soa^polallie P r o d u c t i v i t y The p r o d u c t i v i t y of s o a p o i a l l i e i s shown i n Figure 4 3 . Comparatively l i t t l e y i e l d i s achieved on the open, r e c e n t l y burned area. Production r i s e s s h a rply as the f o r e s t beings to regenerate and u s u a l l y remains high under dense f o r e s t canopies. S o a p o i a l l i e seems to s u r v i v e under these c o n d i t i o n s by growing near major breaks i n the f o r e s t canopy. D. Overstory Community Composition 1. Premier Ridge The seven f o r e s t e d s i t e s on Premier Ridge range i n 8 6 Figure 40. The p r o d u c t i v i t y of forbs on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t ca.nopy. Forest Canopy % 87 Figure 41. The p r o d u c t i v i t y of dwarf shrubs on E s t e l l a Mountain as Influenced by c h a r a c t e r i s t i c stand age and f o r e s t canopy. OJ g W C o •H o T) O U PH 12 10 8 6 4 2 1 T J—"T S 1 f—\ T — 1 S 1 0 1.0 20 30 40 50 60 80 90 100 120 Forest Canopy $ 88 age from 22 to 280 years, spanning a f o r e s t canopy cover from' 26$ to 78$. The most dense stand, 3,4-59 stems per acre, a l s o had the highest f o r e s t canopy, 78$, and i s r e p r e s e n t a t i v e of the lodgepole pine f i r e seres of the southern Rocky Mountain Trench. The climax ponderosa pine s i t e by compari-son had only 74 stems per acre w i t h a. f o r e s t canopy of 38$. In g e n e r a l , ponderosa pine stands occupy more x e r i c s i t e s than the Douglas f i r and tend to have fewer stems per acre and more open canopies. In a d d i t i o n , the f i r s i t e s tend to be c l u s t e r e d near the northern end of the ri d g e whi.ch i s mesic, l a r g e l y due to the m i c r o c l i m a t i c e f f e c t s of a co o l e r exposure. The only western l a r c h occurs i n a s s o c i a t i o n with f i r . s t a n d s at the north end of the r i d g e . 2. E s t e l l a . Mountain The three f o r e s t s i t e s on E s t e l l a Mountain are r e p r e s e n t a t i v e of f o r e s t s of warmer exposure, p a r t i c u l a r l y the southwestern aspects from 4,000 to 7,000 feet i n eleva-t i o n . The c h a r a c t e r i s t i c stand age v a r i e s from 25 to 125 years with a f o r e s t canopy range of 35$ t o 72$. The E s t e l l a Mountain f o r e s t s do not tend to t h i n t h e i r canopy n a t u r a l l y as they mature, but remain r e l a t i v e l y dense, u n l i k e those of Premier Ridge. Consequently only the youngest f o r e s t ( l e s s than 25 years o l d ) e x h i b i t comparatively low f o r e s t 89 Figure 42. The annual p r o d u c t i v i t y of bearberry on E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. 120 , s OJ 100 6 ^—' 80 C o •H -p 6o O •a o 4o u P-, 20 1 -.1 \ \ fs s i—I I 1 I o 20 4o 6o 8o IOO C h a r a c t e r i s t i c Stand Age m 120 120 OJ 6 100 80 o •H -p O • 3 •a o 60 4o 20 e e 1 — 1 — I 8o 90 i o o Forest Canopy % 9 0 Figure 43. The annual p r o d u c t i v i t y of s o o p o l a l l i e (twigs and leaves) as i n f l u e n c e d by c h a r a c t e r i s t i c stand age and f o r e s t canopy. E s t e l l a s i t e s . Table V I I S i t e s t a t i s t i c s f o r trees Premier Ridge 1 9 6 9 . Young Mid. Mature Young Mid. Climax Douglas Douglas Douglas Ponderosa Ponderosa Ponderosa Lodgepole F i r F i r F i r Pine Pine Pine Pine  C h a r a c t e r i s t i c Stand Age 22 55 95 8 0 100 2 8 0 65 Forest Ca;nopy % 26 56 73 49 49 38 78 No. trees per acre 1930 605 331 958 261 47 3459 No, trees i n macroplot 443 139 76 2 2 0 6 0 17 7 9 4 --o No. Douglas f i r 4 3 8 * 1 3 5 * 7 6 * 142 13 4 133 No. Ponderosa pine 3 67 4 7 * .13* 328 No. Lodgepole pine 3 1 3 3 3 * No. Larch 2 1 * denotes curre n t dominants. 92 canopy cover l e s s than 3 5 $ . S e l e c t i v e logging has thinned the canopies of the regenerating f i r s i t e and the l a r c h s i t e . The e f f e c t of t h i s t h i n n i n g i s s i m i l a r to the n a t u r a l t h i n n i n g seen on Premier Ridge, but q u i t e d i f f e r e n t from the e f f e c t s of c l e a r - c u t logging. S e l e c t i v e logging on E s t e l l a has t r i g g e r e d a c t i v e regeneration of Douglas f i r at both the aforementioned s i t e s . The lodgepole pine s i t e r e s u l t s from a hot f i r e which burned up the western exposure of E s t e l l a Mountain i n 1 9 3 1 . The lodgepole s i t e i s on an area p r e v i o u s l y f o r e s t e d by white-barked pine. This stand c o n s t i t u t e s the densest f o r e s t s i t e on the mountain, with 1 , 6 3 4 stems per acre, the lowest being the regenerating f i r s i t e w i t h 5 5 3 stems per acre. The f o r e s t stands on E s t e l l a tend to be composed l a r g e l y of a s i n g l e s p e c i e s , at l e a s t i n i t i a l l y . This i s e s p e c i a l l y t r u e f o r the lodgepole acres which f o l l o w f i r e s . E. S i t e H i s t o r y and the Path of Succession on Premier Ridge In p r i s t i n e times the west and southwest slopes of Premier Ridge were l a r g e l y covered w i t h mature, climax stands of ponderosa pine and Douglas f i r . Moist northern and northeastern slopes were e s t a b l i s h e d to Douglas f i r and l a r c h , f r e q u e n t l y i n dense stands. As aforementioned, logging began on Premier Ridge 93 Table V I I I S i t e s t a t i s t i c s f o r trees E s t e l l a Mountain 1 9 6 9 . Regen. Lodgepole Douglas F i r W. Larch Pine  E l e v a t i o n 4 5 0 0 4 5 0 0 6 0 0 0 C h a r a c t e r i s t i c Stand Age 25 125 35 Forest Canopy f> 35 72 7 1 No. trees per acre 553 1255 1 6 3 4 No. tr e e s i n s i t e 127 2 8 8 375 No. Douglas F i r 1 2 1 * 185 No. Lodgepole Pine 3 19 3 7 5 * No. Larch 3 1 84 * denotes current dominants. 94 about 1910 and was w e l l underway by 1 9 2 0 . The mature f o r e s t s of ponderosa. pine and Douglas f i r were removed from a l l but a few r e l a t i v e l y i s o l a t e d or i n a c c e s s i b l e areas of the r i d g e . V i r t u a l l y a l l of the l a r g e Douglas f i r was cut at t h i s time. Table IX shows the number of stumps by species present at the s i t e s s e l e c t e d f o r i n t e n s i v e examination.• Table X traces the h i s t o r y of each s i t e as f a r back as p o s s i b l e . In most cases the nature of the mature f o r e s t (ca. 2 0 0 years o l d ) can be determined from the stumps which have remained s i n c e the logging of the e a r l y 1 9 0 0 ' s . Thus i t i s p o s s i b l e to determine g e n e r a l l y the nature of a. f o r e s t cover which began to develop about 1700 A.D. Logging of the mature, climax f o r e s t r e s u l t e d i n the regrowth of a stand of s i m i l a r species composition i n most cases.. P o s s i b l y a s l i g h t i n c rease i n p r e c i p i t a t i o n over the l a s t few decades has r e s u l t e d i n an increase In the numbers of young Douglas f i r i n stands which were mixed w i t h pine and f i r . In some cases, r e c e n t l y cut ponderosa pine stands which were not burned have become e s t a b l i s h e d to Douglas f i r . The water t a b l e i n the area may a l s o r i s e as shown by the r i s i n g water l e v e l of A l k a l i Lake. Since the climax montane f o r e s t c o n s i s t s of an i n t e r g r a d e of ponderosa pine and D o u g l a s . f i r , o c c u r r i n g i n mixed stands, or occasion-a l l y i n pure stands of e i t h e r s p e c i e s , an increase i n moisture might s h i f t the species, establishment patterns i n favour of 95 Douglas f i r . Ponderosa pine i s very c l o s e to i t s northern l i m i t i n the Southern Rocky Mountain Trench. F i r e i n these stands i s followed "by the e s t a b l i s h -ment of pine i n most cases. A more severe f i r e i s needed to e l i m i n a t e the ponderosa pine due to i t s loose, f i r e r e s i s t a n t bark, however a s u f f i c i e n t l y hot ground f i r e i n the climax pine f o r e s t may t r i g g e r an understory of lodgepole pine. Dense stands of lodgepole pine f r e q u e n t l y contain young ponderosa pine and Douglas f i r t r e e s . Appar-e n t l y , i t takes about 120 years on most s i t e s , without f i r e , f o r the lodgepole to t h i n s u f f i c i e n t l y to permit f i r or ponderosa pine to become dominant. Lodgepole veternas up to l 8 0 years o l d may be found i n regenerating ponderosa pine and Douglas f i r stands, i n d i c a t i n g the e a r l i e r pressure of f i r e at the s i t e . S e r a i grasslands may form a d l s c l i m a x f o r s e v e r a l decades on d r i e r slopes f o l l o w i n g the removal of the mature f o r e s t . The open t e r r a c e area of Premier Ridge followed t h i s p a t t e r n . However, young Douglas f i r s have become esta-b l i s h e d i n moist g u l l i e s and i n time w i l l reinvade the area formerly occupied by the f o r e s t . F. S i t e H i s t o r y and the Paths of Succession on E s t e l l a Mountain Logging has exerted only a minor i n f l u e n c e on the south and southwestern slopes of E s t e l l a Mountain. C u t t i n g Table IX S t a t i s t i c s for stumps, Premier Ridge, 1969. No. stumps per acre No. stumps In macroplot No. D. F i r stumps No. P. Pine stumps No. Larch stumps No. Lodgepole Pine stumps Rel i c t Douglas F i r Ponderosa Pine Agropyron Purshla Poa-stlpa Young Middle Mature Young Middle Climax Lodgepole Pine 13 3 *3/l4.7 139 9 22 9 9 32 2 5 2 2 32/14.7 2/N.A. 4/15.2 2/18.5 2/N.A. 1/13.0 . 9 2 2/18.2 0 0 2/24.3 ON * Note: 3/14.7 numerator = no. stumps denominator = average diameter of stump 1" off ground In Inches. Table X F o r e s t cover of Premier Ridge s i t e s , past and p r e s e n t . S i t e Name Previous F o r e s t Nature of D i s t u r b a n c e R e l i c t bluebunch-wheatgrass B i t t e r b r u s h B l u e g r a s s - n e e d l e -g r a s s Young Douglas f i r Mid. Douglas f i r Mature Douglas f i r Yg. Ponderosa Pine Open mature Douglas f i r Dense mature Dougla.s f i r Open climax Douglas f i r Semi-open climax Douglas f i r Open climax Douglas f i r Probably dense mature f i r Open climax Ponderosa Pine C l e a r cut & burned 1920 C l e a r cut & burned 1920 C l e a r cut & burned 1920 S e l e c t i v e l o g g i n g 1920 & 1965 S e l e c t i v e l o g g i n g 1920 to present N.A. C l e a r cut 1920 Mid. Ponderosa Pine S e r a i g r a s s l a n d Increase ppt. (?) Climax Ponderosa Pine Lodgepole Pine N . A . None Open climax Ponderosa Burned 1931 Pine Present Cover Bunchgrass s e r e Shrub & s e r a i g r a s s l a n d Shrub & s e r a i g r a s s l a n d Regen. Douglas f i r & vet e r a n s Regen. Douglas f i r ^ ( a l l ages) Dense Mature Douglas f i r Yg. Ponderosa Pine & Douglas f i r regen. Mature stand Ponderosa Pine . Open climax montane f o r e s t Dense Lodgepole Pine & o l d Ponderosa Pine v e t e r a n s w i t h some Douglas f i r regen. TABLE XI THE PATHS OF SUCCESSION ON PREMIER RIDGE SELECTIVE LOGGING MAINTAINS YOUNG TO MATURE STAND OF DOUGLAS FIR AND PONDEROSA PINE WITH SOME OLD VETERANS 100-200 YEAR CYCLE DEPENDING UPON ASPECT Climax Montane Forest si Lodgepole pine forest Open brush & serai grassland DISCLIMAX MAINTAINED BY SITE MOISTURE AND GRAZING PRESSURES Table X I I S t a t i s t i c s f o r stumps, E s t e l l a Mountain, . 1969 S e r a i Bluebunch S e r a i Regen. • Wheatgrass Fescue Lodgepole Douglas F i r Larch No. stumps per acre 44 88 57 88 26 No.' stumps per s i t e 10 20 13 20 6 No. Douglas f i r stumps 13/12.6 3/23.3 No. WB pine stumps 10/6.5 18/14.8 13/12.1 No. Lodgepole pine stumps No. Larch stumps 1/16.1 7/12.6 3/18.8 Note: numerator = No. stumps denominator = average diameter i n inches 1 foot from ground l e v e l Table X I I I Forest cover of E s t e l l a . Mountain, past and present. S i t e Name Regen. Douglas f i r Larch s i t e . Lodgepole Pine S e r a i fescue S e r a i bluebunch wheatgrass Previous Forest Semi-open mature Douglas f i r Dense Larch Mature WB pine stand Mature WB pine f o r e s t Mature WB pine f o r e s t Nature of Disturbance S e l e c t i v e logging 1952 S e l e c t i v e logging 1952 Burned 1931 Burned 1931 Burned 1931 Present Cover Semi-open mature Douglas f i r Larch w i t h Douglas . f i r understory Dense Lodgepole Pine f o r e s t S e r a i grassland w i t h WB pine seedlings S e r a i grassland with WB pine seedlings 101 has been concentrated on the more productive n o r t h and n o r t h -western slopes which are dominated by Englemann spruce. The south and southwestern slopes are e s t a b l i s h e d to Douglas f i r w i t h some s e r a i stands of western l a r c h . The area on these aspects above 5 * 0 0 0 f e e t was p r e v i o u s l y covered by a f o r e s t of white-barked pine. The regenerating Douglas f i r s i t e was s e l e c t i v e l y cut about 1952 and i s c u r r e n t l y regenerating to Douglas f i r . The l a r c h s i t e i s a l s o i n the Douglas f i r zone and was s e l e c t i v e l y cut about 1 9 5 2 . This t h i n n i n g has favoured an xmderstory of Douglas f i r . These trees w i l l , doubtless i n time, e l i m i n a t e or reduce the now dominant l a r c h . Scattered o l d ( l 8 0 years) lodgepole pines at both of these sutes suggest that they were probably burned over 2 0 0 years ago. The remaining three s i t e s on E s t e l l a Mountain were e s t a b l i s h e d on the burn of 1931 which completely destroyed the white-barked pine f o r e s t . The lodgepole pine s i t e i s r e p r e s e n t a t i v e of the areas which were r e f o r e s t e d s h o r t l y a f t e r the burn. Stumps of any f o r e s t which might have e x i s t e d p r i o r to the white-barked pine f o r e s t could not be found. Neither white-barked pine seedlings nor the seedlings of any other c o n i f e r could be found under the dense stands of lodgepole pine. These seedlings are, however, now be-coming evident i n open areas which were burned but f o r some TABLE XIV THE PATH OF SUCCESSION ON ESTELLA MOUNTAIN (SW & S aspect) i DOUGLAS FIR ZONE Larch Lodgepole pine forest o serai grassland DISCLIMAX ACCORDING TO SITE PPT (ASPECT) 100 YEAR MAXIMUM CYCLE 11 WHITE-BARKED PINE ZONE Mature White-bark pine Forest Lodgepole pine forest Serai grassland 80 YEAR MAY CYCLE DISCLIMAX DEPENDENT UPON SITE AND PPT. AND ASPECT 10.4 reason (o f t e n aspect) have f a i l e d to regenerate to lodge-pole pine. G. The P r o d u c t i v i t y of the Forest 1. Premier Ridge No attempt was made to determine the t o t a l annual or net p r o d u c t i v i t y of the f o r e s t . The methods r e q u i r e d to measure needle f a l l , "branch growth and root growth were beyond the scope of t h i s i n v e s t i g a t i o n . For comparative examination of the s i t e s , the t o t a l volume of timber was. determined i n each macroplot and subsequently converted to acre u n i t s . The average annual increment was a l s o recorded. These data g i v e some i n d i c a t i o n of the f o r e s t biomass which i s being maintained at each s i t e and the r a t e at which i t i s i n c r e a s i n g . Table XV l i s t s the f o r e s t p r o d u c t i v i t y data f o r Premier Ridge. The t o t a l volume of timber increases w i t h age, apparently reaching a peak i n the mature Douglas f i r s i t e which had 3 , 5 9 3 cubic f e e t of stem wood. This s i t e was beginning to t h i n i t s e l f and the centres of many of the l a r g e r trees showed signs of r o t , reducing t h e i r commercial value. The ponderosa pine s i t e s c o n t a i n much l e s s timber volume than the corresponding Douglas f i r s i t e s . The climax ponderosa pine s i t e had a lower timber volume and a much lower annual increment (5.7 cu f t / a c ) than any of the other pine s i t e s . In s p i t e of x e r i c nature of the s i t e , lodgepole Table XV S t a t i s t i c s r e l a t i n g to wood production, Premier Ridge s i t e s . CD CD c 1 •u i u Mat. D. Fir CD c CD C 1 ' Lodgepole P" Yg. D. Fj Mid D. Fj Mat. D. Fir Yg. P. Pj •r-i PH .P-i xi •H s 1 1 Climax P. 1 ' Lodgepole P" No. stems per acre 1930 605 331 958 261 74 3459 C h a r a c t e r i s t i c sta.nd age 22 55 95 80 100 280 65 Forest canopy % 26 56 73 • 49 49 38 78 DBH area per acre 4oo 91 161 130 109 74 701 Mean DBH area . 2 1 .15 . 4 9 .15 . 4 2 1 .0 . 2 0 T o t a l wood volume f t 3 1115 892 3593 919 1729 1573 l 4 l i Annual increment* f t 3 5 0 . 5 1 6 . 5 3 7 . 5 1 1 . 3 1 6 . 6 5 . 7 2 1 . 3 annual increment = t o t a l wood volume ( f t 3 ) c h a r a c t e r i s t i c stand age ( y r . ) . i o 6 pine stands showed a good annual increment (21.3 cu f t / a c ) . 2. E s t e l l a Mountain The p r o d u c t i v i t y data f o r the timber of the E s t e l l a Mountain s i t e s i s recorded i n Table XVI. The number of stems per acre of the E s t e l l a s i t e i s s i m i l a r to those s i t e s of corresponding age on Premier Ridge. N a t u r a l t h i n n i n g of mature stands does not occur and these o l d e r stands tend to be more dense than t h e i r lower e l e v a t i o n counterparts. The volume of timber on the young stands on E s t e l l a and Premier are comparable. The regenerating f i r stand on E s t e l l a had a: volume of 9 6 7 cubic feet of wood whi l e the young Douglas f i r stand on Premier had a wood volume of 1 ,115 cubic f e e t . At maturity the D o u g l a s - f i r and l a r c h f o r e s t s of E s t e l l a y i e l d volumes of timber higher than the mature f i r stands on Premier, although the "mature Douglas f i r " s i t e on the northeast slope of Premier produced a s u b s t a n t i a l volume of timber (3,4-93 f t . ) due to i t s moist aspect. The E s t e l l a f o r e s t grows more q u i c k l y than those of Premier Ridge. At an age of 35 years they have surpassed the t o t a l wood y i e l d s of the lower e l e v a t i o n s . The annual increment of the lodgepole pine stand on E s t e l l a was 6 7 . 5 ft/year,' the highest measured during t h i s study. D i f f e r e n c e s i n s t o c k i n g d e n s i t y and species compo-s i t i o n of the f o r e s t s made f u r t h e r comparison somewhat d i f f i -c u l t . 107 Table XVI S t a t i s t i c s r e l a t i n g to wood production, E s t e l l a Mountain s i t e s . Regen. D. F i r Larch Lodgepole Pine No. stems per acre 573 1633 1254 C h a r a c t e r i s t i c stand age 25 125 35 Forest canopy % • 35 72 71 T o t a l DBH area per acre 126 266 170 Mean DBH area . 2 4 . 2 1 .11 T o t a l wood volume per acre ( f t 3 ) 967 3 3 3 2 2365 Annual increment* per acre _ 3 8 . 3 2 6 . 6 6 7 . 5 * annual increment = t o t a l wood volume ( f t 3 ) c h a r a c t e r i s t i c stand age ( y r . ) 108. H. Aggregate Understory P r o d u c t i v i t y I. Premier Ridge The t o t a l annual understory p r o d u c t i v i t y i s presented i n two forms; one, c o n s i d e r i n g i t s r e l a t i o n s h i p w i t h c h a r a c t e r i s t i c stand age, and two, c o n s i d e r i n g i t s r e l a t i o n s h i p w i t h f o r e s t canopy. The e f f e c t of c h a r a c t e r i s t i c stand age on the understory p r o d u c t i v i t y i s shown i n Figure 4 5 , i n c l u d i n g , f o r comparative purposes, the production of the n a t u r a l • grassl a n d . The p r o d u c t i v i t y of the three open s e r a i s i t e s averages 7 1 . 7 gm/m2 ( 6 3 8 l b / a c ) . Grasses form the l a r g e s t component of t h i s y i e l d . The p o t e n t i a l p r o d u c t i v i t y of these areas (under a b e t t e r g r a z i n g regime) i s probably about 150 gm/m2 ( 1 , 3 3 4 l b / a c ) . T o t a l p r o d u c t i v i t y increases s l i g h t l y as f o r e s t regeneration commenced. This r i s e was largeLy due to In-creases i n the bearberry and s o a p o i a l l i e y i e l d s . The grass component and the b i t t e r b r u s h components, which are h e a v i l y used by gr a z e r s , decreased sh a r p l y i n y i e l d . The stands from 5 0 to 100 years of age show depressed t o t a l p r o d u c t i v i t y reaching only 5 6 $ of the aggregate production of the open s e r a i communities. A l l components showed a decrease i n production and i n extreme cases a component or species may a c t u a l l y disappear e n t i r e l y . Forbs may-be abundant on moist 1 0 9 s i t e s . As the f o r e s t matures and approaches the climax s t a t e , the t o t a l p r o d u c t i v i t y increases l a r g e l y due to n a t u r a l t h i n n i n g . The h e l i o p h y t e s reappear and make s i g n i f i c a n t c o n t r i b u t i o n s to increase the y i e l d . The f o r b s , bearberry and b i t t e r b r u s h f r a c t i o n s a l l increased markedly i n the climax f o r e s t . However, grass production i n the climax stand remains low, a c h i e v i n g only 5 0 $ of the y i e l d a t t a i n e d on the unforested s i t e s . F igure 44 shows the r e l a t i o n s h i p between understory p r o d u c t i v i t y and f o r e s t canopy. Under a canopy cover of 2 o $ the aggregate p r o d u c t i v i t y increases s l i g h t l y , due to increases i n y i e l d by bearberry and s o a p o i a l l i e . Forest canopy values greater than 5 0 $ are a s s o c i a t e d with, a reduced p r o d i r t i v i t y of the understory. Production under the higher f o r e s t canopy values ( 7 2 $ and 7 8 $ ) was reduced to 6 0 $ of that of the nonforested communities. The grass component d e c l i n e d s t e a d i l y as the f o r e s t canopy increased. The 1 0 0 $ Increase i n pro-d u c t i v i t y of the open f o r e s t stands ( 2 6 $ and 3 8 $ canopy) i s due to an increase i n bearberry. The annual increment of the timber.at each s i t e has not been included i n Figure 4 4 . Apparently bearing l i t t l e r e l a t i o n s h i p to understory y i e l d s , the increment of timber d e c l i n e s r a t h e r s t e a d i l y , being highest i n the young-CT I ro VJ1 o H O o o 1 i * | n a t u r a l grassland ro o *1 o •i (D ct o cu o «<5 o 4=r O U l o O A o o zarzi IM o P 4 cn cr CQ co CD CQ co o 4 c cr CO Lx) Ct Ct CD c 4 si co 02 O o o P H I—1 h" CD tri CD pj 4 0) 4 TO 4 CD H* (-3 3 p~ CD I—1 £ PJ fij CT o 4 CD CD CLCT P cr c t << CD M} 03 o b CD £ W P c t H o co O 5 CL CD 4 CQ • Ct O >-S 0<< r< 4 O 3 a P C CP. o o ct 4 H* <! O f O Ct 3 o o CD 3 i-d ct 4 CO CD „ B P p. 4 CD CD 4 O ft) 3* H-P D-, 4 CT P CD O Ct CD CD CO 4 N CD a o n 150 100 gm/m" 5 0 F i g u r e 4 5 F i g u r e 4 5 The a g g r e g a t e a n n u a l u n d e r s t o r y p r o d u c t i v i t y o f P r e m i e r Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c s t a n d age shown. The a g g r e g a t e a n n u a l u n d e r s t o r y p r o d u c t i v i t y o f P r e m i e r Ridge as i n f l u e n c e d by c h a r a c t e r i s t i c s t a n d age. Only major components a r c shown. n l l l i 20 30 I 4 0 Only major components a r e B i t t e r b r u s h Dwarf Shrubs ^ S o o p o l a l l i e Forbs Grass B e a r b e r r y I 5 0 6 0 / C h a r a c t e r i s t i c Stand Age •-3 w CQ cd Q •-3 O CD H- o P c t P ro. c t P P cr P • 'ri. c t cr i—i cr rr CD •D cn CD CD CD 4 cr CA J>d QJ rr <j H- H P cn H 13- cr C O o 00 oo H UJ 03 4=r oo U l I—1 t - 1 oo oo ro U l o Ul ro CT\ 4^-OO H —«3 i i i o o Skookumchuck P r a i r i e ro oo o^ 0> C O OO Ul oo H OO 4^ 4=" 4=" C O -<1 O Ul o u i 4=- ro o oo o co u i ro H oo 00 ro CT\ u i 4=-o-> u i ro M o vo H ON u i H H 1 U l i~3 i-3 ro H ^o o\ 1-3 ro ro 4=- 4=-ro ro H vo o vo M ro H O^ O H OO 4=- 00 Ul H> 0^  ro o vo oo o i — 1 4=-O ro u i R e l i c t Agropyron Purshia Poa-stipa Yg. D. P i r Mid D. F i r Lodgepole Yg.. P. Pine Mat. D. F i r Mid P. Pine Climax .i-3 tr ro P 09 >s CD 09, P c t ro P P ro co c t O << <n 4 o a-d o c t H » <J H-C t ^ O ro 3 ro oq CD SIT 1 : L 3 est stand and lowest i n the o l d e s t . One d e v i a t i o n from t h i s trend i s the mature Douglas f i r (age 95 years) which i s located on the moist northeast slope and would consequently be expected to grow more r a p i d l y . 2 . E s t e l l a Mountain The net annual understory p r o d u c t i v i t y of E s t e l l a Mountain f o l l o w s a p a t t e r n s i m i l a r to t h a t found on Premier Ridge. Open areas g e n e r a l l y produce high y i e l d s , of herb-aceous s p e c i e s , w h i l e the f o r e s t s i t e y i e l d s tend to be reduced p r i n c i p a l l y i n the grass component. The increased y i e l d of herbaceous species noted i n young regenerating stands on Premier Ridge, was repeated on E s t e l l a . However, a l l of the increased p r o d u c t i v i t y at the 25 year o l d s i t e r e s u l t e d from bearberry. The dwarf shrub component was sharply reduced at o l d s i t e s w i t h high f o r e s t canopy values. The e f f e c t of the f o r e s t canopy on the understory p r o d u c t i v i t y i s shown i n Figure 4 7 . The net understory p r o d u c t i v i t y d e c l i n e s as f o r e s t regeneration commences. The increase i n y i e l d at 3 5 $ cover i s e n t i r e l y due to bear-b e r r y . The dense stands y i e l d only 4 7 $ as much per annum as do the open s i t e s . The g r eatest reductions occur i n the grass and shrub components. Figure 4 7 does not i n c l u d e the annual increment of the timber at each s i t e . The highest annual timber increment observed i n the study was found at the r a p i d l y Figure 46. The aggregate annual understory p r o d u c t i v i t y of E s t e l l a Mountain as i n f l u e n c e d by c h a r a c t e r i s t i c stand age. Only major | | Bearberry components are i n c l u d e d . S o a p o l a l l i e Dwarf Shrubs 2 0 0 jgjggl Forbs ywA Grass 150 gm/mc 100 H 5 0 I 0 • I 25 T" 50 I 75 T 100 1 125 1 150 C h a r a c t e r i s t i c Stand Age F i g u r e 47 F i g u r e 47. 2 0 0 150 gm/m£ 100 50 J 0 The a g g r e g a t e a n n u a l u n d e r s t o r y p r o d u c t i v i t y o f E s t e l l a Mountain as i n f l u e n c e d by f o r e s t canopy. Only major components a r e shown. The a g g r e g a t e a n n u a l u n d e r s t o r y p r o d u c t i v i t y o f E s t e l l a Mountain as i n f l u e n c e d by f o r e s t canopy. Only major components a r e shown. 10 2 0 T" 3 0 J 1 4 0 5 0 ml Grasses m Forbs mi Dwarf Shrubs • S o a p o i a l l i e • B e a r b e r r y 6 0 H H 8 0 F o r e s t Canopy % Table XVIII The aggregate annual understory p r o d u c t i v i t y of E s t e l l a Mountain SITE NAME Se r a i S e r a i Fescue Bluebunch . Wheatgrass Regen. D. F i r Lodgepole Larch Grass 75 31 40 15 3 4 Forb 24 15 15 " l l 5 Dwarf shrub 3 11 6 12 2 S o a p o l a l l i e 1 7 . 4 T 9.0 4 . 6 2 . 5 Bearberry 14 - 114 1.0 2 T o t a l 1 3 3 . 4 57 184.0 4 3 . 6 4 5 . 5 Wt. i n gm/m' 117 growing lodgepole pine s i t e (age 35 y e a r s ) . The o l d e r s i t e s show a r e d u c t i o n i n production, but remain higher than the r a t e of production observed on Premier Ridge. 118 rv DISCUSSION The v e g e t a t i o n patterns of the trench f l o o r r e -f l e c t the previous i n f l u e n c e s of man. The logging of the e a r l y 1 9 0 0's and the f i r e s of the 1 9 3 0 ' s have l e f t a patch-work of f o r e s t and open areas of v a r y i n g stages of the succession. These areas are i n a s t a t e of dynamic pro-g r e s s i o n ; most of the area i s p o t e n t i a l f o r e s t and i t i s t h i s d i r e c t i o n that the progression or succession i s moving. C a t t l e and w i l d ungulates p r e v i o u s l y r e s t r i c t e d i n the area, are c u r r e n t l y e x p l o i t i n g these unforested s e r a i rangelands. The previous existance of f o r e s t s on these lands i s s t r o n g l y evidenced by the stumps which have remained i n t a c t , photo-graphs and the records of f i r e and logging of the area. ': S i m i l a r records e x i s t f o r the east w a l l of the tre n c h . The most n o t i c e a b l e e f f e c t of the regrowth of the f o r e s t on areas which f o r some twnty to f o r t y years have remained without t r e e s , i s a r e d u c t i o n i n the pro-d u c t i v i t y of the understory community upon which the grazers l a r g e l y depend. The p a t t e r n of regeneration has been one i n which the more moist aspects, such as the northeast and east slopes, stream channels and small draws have been invaded f i r s t . Thus the trees tend to cir c u m s c r i b e areas then c l o s e i n the remaining spaces. This i n v a s i o n has proceeded so g r a d u a l l y that i t f r e q u e n t l y goes unnoticed. 119 D i v e r s i t y i n c l i m a t e , v e g e t a t i o n and s o i l prevented the use of a system f o r randomly l o c a t i n g s i t e s f o r i n t e n s i v e study. The s i t e s were c a r e f u l l y s e l e c t e d a f t e r general study. D u p l i c a t i o n of the exclosures was not p o s s i b l e due to the cost r e q u i r e d f o r t h e i r c o n s t r u c t i o n . 1. The Premier Ridge Area The removal of the mature montane f o r e s t from Premier Ridge between 1910 and 1 9 2 0 , and the subsequent f o r e s t f i r e s led to the establishment of communities w i t h -out trees on v a r i o u s p a r t s of the r i d g e w h i l e on other p a r t s regeneration of f o r e s t commenced almost immediately. The f l o r i s t i c composition of the unforested s e r a i communities has been a l t e r e d by g r a z i n g i n many regions. However, the r e l i c t Agropyron s i t e has r e c e i v e d l i t t l e g r a z i n g by domestic stock. At present, 40 years a f t e r the l a s t major f i r e and s i x t y years a.fter l o g g i n g , t h i s s i t e had developed a cover of bluebunch wheatgrass ( 5 0 $ ) and junegrass ( 9 $ ) . Few other grass species and very few forbs are present at the s i t e . Under prolonged p r o t e c t i o n from g r a z i n g and without the i n v a s i o n of t r e e s , t h i s s i t e i s beginning to take on the c h a r a c t e r i s t i c s of a. n a t u r a l grassland s i m i l a r i n nature to the Skookumchuck P r a i r i e . Since t h i s i s p o t e n t i a l l y f o r e s t land, the Agropyron-Koeleria community might be i n t h i s case termed as d i s c l i m a x . On the adjacent unforested lands 120 communities of Poa spp. and S t i p a spp. are common. The i n i t i a t i o n of f o r e s t growth on these s i t e s has a pronounced a f f e c t on the f l o r i s t i c s of the grassy s e r a . Bluebunch wheatgrass, Kentucky bluegrass and Canada bluegrass disappear r a p i d l y ; rough fescue and junegrass may l i n g e r on i n the for e s t e d s i t e s but disappear as the canopy exceeds 60$. Pinegrass, u s u a l l y only an o c c a s i o n a l or r a r e species i n the unforested community, increases r a p i d l y as the f o r e s t regenerates, forming the only grass present under very dense f o r e s t canopies. To the ca s u a l observer, the r e l a t i v e change i n abundance of grass species as the f o r e s t develops i n the f o r e s t e d s i t e s may go unnoticed. Forbs were v a r i a b l e i n abundance throughout the succession; as with grasses, h e l i o p h y t e s predominated on the unforested areas but g r a d u a l l y g i v e way to the sciophytes as the f o r e s t developed. The more h e a v i l y grazed.unforested s i t e s had many more species (22) than d i d the l i g h t l y grazed open areas ( 5 ) . The shrubs were most abundant on the un-for e s t e d areas and e a r l y i n the f o r e s t seres; as f o r e s t canopy readings exceeded 50$ shrub abundance d e c l i n e d . B i t t e r -brush was noted to be very i n t o l e r a n t . On the other hand, s o a p o i a l l i e was more abundant In the timbered areas, o f t e n e x i s t i n g under major breaks i n the f o r e s t canopy. Bear-berry was most common on the open communtles, but was common 121 In the very young stages of f o r e s t regeneration; i t d e c l i n e d again under very dense f o r e s t canopies. The p r o d u c t i v i t y of the communities of the un-fo r e s t e d areas was g e n e r a l l y depressed by previous g r a z i n g . Probably few s i t e s were producing near optimum l 8 0 gm/m2 ( 1 , 6 0 0 lb/ac.) of which these fenced s i t e s are capable. The r e l i c t Agropyron community produced 65 gm/m2 ( 5 7 9 lb/ac.) of grass; t h i s y i e l d appeared to drop to 34 gm/m2 ( 3 0 7 l b / a c . ) as f o r e s t regeneration began and continued t o d e c l i n e , reach-ing a low of 12 gm/m2 (107 l b / a c ) . Production i n the climax f o r e s t appeared to r i s e to 25 gm/m2, although t h i s q u a n t i f i -c a t i o n of the d e c l i n e i s approximate and although i t may be modified by changes i n f l o r i s t i c composition. The p r o d u c t i v i t y of the forbs i s seemingly l i t t l e a f f e c t e d i n the general p a t t e r n of the succession. The only notable exception was i n the climax ponderosa pine stand where forb production was highest ( 4 0 gm/m2 356 l b / a c ) . In s p i t e of the r e l a t i v e l y low y i e l d of forbs when compared to grasses, they are undoubtedly used by mule deer and white-t a i l e d deer e a r l y i n the s p r i n g as the grass i n i t i a t e s growth. The y i e l d by bearberry was highest under open f o r e s t where canopies range from 2 0 $ to 4 0 $ ; on these s i t e s the y i e l d was about 6 0 gm/m2 ( 5 3 4 l b / a c ) . B i t t e r b r u s h production (annual twigs of l e a f and wood) was highest i n the unforested s i t e s and d e c l i n e r a p i d l y 122 as f o r e s t r e gernation began. The three unforested s i t e s y i e l d e d 6 . 3 , 1 4 . 1 and 4 . 8 gm/m2 with an average of 8 . 4 gm/m2 (75 lb/ac.) of b i t t e r b r u s h . The production i n climax f o r e s t was 9 . 0 gm/m2 ( 8 0 l b / a c ) . Production on the other f o r e s t e d s i t e s d i d not exceed 2 . 5 gm/m2 ( 2 2 l b / a c . ) B i t t e r b r u s h i s h e a v i l y used on the unforested areas of the r i d g e and p r o t e c t s (from grazing) many of the grasses which develop under i t s canopy. On the h e a v i l y grazed s i t e s most of the grass p r o d u c t i v i t y i s r e a l i z e d under the b i t t e r b r u s h p l a n t s where i t i s not a v a i l a b l e to g r a z e r s . • • , S o a p o i a l l i e production on the three unforested s i t e s averaged 5 . 2 gm/m2 (46 lb/ac.) and reached i t s highest y i e l d i n the e a r l y stages of f o r e s t regeneration, 3 0 gm/m2 ( 2 6 7 l b / a c ) . As the succession proceeded beyond t h i s stage production of s o a p o i a l l i e d i d not exceed 2 . 5 gm/m2 ( 2 2 l b / a c ) The f o r e s t stands s e l e c t e d f o r study on Premier Ridge included Douglas f i r ( 3 ) * ponderosa pine ( 3 ) and lodgepole pine ( l ) . The number of stems per acre f o r each corresponding age of t h e succession was highest f o r lodge-pole p i n e , followed by Douglas f i r . Ponderosa pine had the ' lowest number of stems per acre. The annual Increment of wood production f o r t h e f o r e s t s i t e s v a r i e d from 5 0 . 5 f t ^ / year i n the young Douglas f i r stand to 5 - 7 ft , 3/year i n the climax f o r e s t . The timber volume per acre ranged from 8 9 2 ft - 3 to 123 to 1 , 7 2 9 f t ^ on the west s i d e of the r i d g e . The only mature Douglss f i r s i t e which could be found was on the northeast side of the r i d g e . I t s t o t a l volume was 3 , 5 9 3 f t 3 and a t an age of 95 years the annual increment of t h i s stand was 3 7 . 5 f t 3 / y e a r , r a t h e r high when compared to the west side f o r e s t s of s i m i l a r age. While the south and western aspects are not s u i t e d to the r a p i d production of timber, the n o r t h and east slopes grow trees q u i c k l y . This f a c t may be u s e f u l i n the formulation of i n t e g r a t e d land use p o l i c i e s f o r such areas. The net understory p r o d u c t i v i t y of the unforested s i t e s averaged 75 gm/m2 ( 8 3 9 l b / a c ) . This value increased to l 4 5 gm/m2 ( 1 , 2 9 1 l b / a c ) as f o r e s t regeneration commenced. In o l d e r stands the net understory p r o d u c t i v i t y decreased to l e s s than 40 gm/m2 ( 3 5 6 l b / a c ) . As these stands reach m a t u r i t y and n a t u r a l t h i n n i n g occurs, a gradual increase i n net understory p r o d u c t i v i t y occurs. The climax stand of ponderosa pine exceeded the net p r o d u c t i v i t y of any other s i t e y i e l d e d 147 gm/m2 ( 1 , 3 0 8 l b / a c ) . However i t i s Important to r e c a l l that the most v a l u a b l e component to the g r a z i n g animal (the grasses, forbs and b i t t e r b r u s h ) a l l decrease markedly as regeneration of the f o r e s t begins. The Increases i n y i e l d are l a r g e l y a t t r i b u t a b l e to bearberry and s o a p o i a l l i e which exxjerience l i t t l e g r a z i n g . Furthermore the 124 grass of the f o r e s t e d s i t e s i s pinegrass which has l i t t l e or no n u t r i t i o n a l value as a wi n t e r forage and f r e q u e n t l y i s not a v a i l a b l e beyond September or l a t e August when i t s n u t r i t i o n a l value drops r a p i d l y and i s beaten down by f a l l r a i n s and snow storms. 2 . The E s t e l l a Mountain Area The E s t e l l a s i t e s have not been grazed by domestic stock. The two major f a c t o r s governing t h e i r present s t u r c t u r e were the s e l e c t i v e logging about 1952 and the f i r e s of 1 9 3 4 . The e f f e c t of e l e v a t i o n i s a prime inherent h a b i t a t f a c t o r f o r the E s t e l l a s i t e s . The f l o r i s t i c s of the unforested areas of E s t e l l a Mountain are not d i s s i m i l a r to those of the Premier Ridge area. Bluebunch wheatgrass or rough fescue u s u a l l y domin-ate the community; s e v e r a l other grasses were i n some e v i -dence. At the 5 , 9 0 0 foot e l e v a t i o n , the dominant bunchgrass was rough fescue; at 6 , 2 0 0 f e e t . i t was wheatgrass. At t h i s l a t t e r e l e v a t i o n the abundance of the herbaceous cover was d i s t i n c t l y l e s s than that at 5 , 9 0 0 f e e t . Pinegrass was present in. the unforested communities i n small, amounts ( 5 $ cover) but Increased ( 3 5 $ cover) as f o r e s t regeneration began. Rough fescue and wheatgrass became markedly reduced and e v e n t u a l l y disappeared as the f o r e s t canopy developed.. Pinegrass i s the most evident grass species present i n dense stand of t r e e s . 125 Forbs were g e n e r a l l y abundant at a l l s i t e s on E s t e l l a and no trends i n abundance were d i s c e r n a b l e . How-ever, given time, t h e bunchrass community below 6 , 0 0 0 f e e t may develop as a d i s c l i m a x community s i m i l a r to some on Premier Ridge; i n the seres to f o l l o w forbs may be reduced i n the unforested communities. This i s u n l i k e l y , however, as t r e e regeneration may occur on these s i t e s before s u f f i c i e n t time has passed to e s t a b l i s h a "grassland" d i s c l i m a x community. The shrubs on E s t e l l a showed no major trends with regard to the succession. S o a p o i a l l i e was found i n the dense stands of lodgepole pine where i t e x i s t s p r i m a r i -l y under gaps i n the overstory canopy. P r o d \ A c t l v i t y of the grasses on the unforested s i t e s was s i m i l a r to that on Premier Ridge. At 5 , 9 0 0 f e e t the y i e l d was 75 gm/m2 ( 6 6 8 lb/ac.) but had dropped to 31 gm/m2 ( 2 6 2 lb/ac.) at 6 , 2 0 0 f e e t . The y i e l d of grasses d e c l i n e d r a p i d l y as f o r e s t regeneration occurs. T h i r t y f i v e years a f t e r regeneration began, the p r o d u c t i v i t y of the grass component was 15 gm/m2 ( 1 3 ^ l b / a c . ) . This r a p i d d e c l i n e i s due to the very r a p i d growth of the trees once they be-came e s t a b l i s h e d . At these e l e v a t i o n s p r e c i p i t a t i o n i s a f f e c t i v e throughout the summer and thus the growing p e r i o d Is extended i n t o summer beyond that found at the v a l l e y bottom e l e v a t i o n s where growth Is c u r t a i l e d by mid J u l y . Forb p r o d u c t i v i t y d e c l i n e s as the succession progresses, 126 being highest on the unforested s i t e s , 24 and 15 gm/m2 averaging 15 gm/m2 ( 1 3 5 lb/ac.) and changed l i t t l e under the high f o r e s t canopy v a l u e s , 15 gm/m2 ( 1 2 5 l b / a c ) . Dwarf shrubs a l s o d e c l i n e s t e a d i l y as the succession proceeds. Bearberry y i e l d s were highest i n the middle f o r e s t canopy range, sometimes as high as 120 gm/m2 ( 1 , 0 6 8 l b . a c ) . S o a p o l a l l i e produced very l i t t l e (17 gm/m2 ( 1 5 1 lb/ac.) on the unforested areas. The y i e l d Increased as the f o r e s t canopy developed. Representative y i e l d s f o r the timbered areas were about 45 gm/m2 ( 4 0 1 l b / a c ) . The timber production on E s t e l l a was, as might be expected from p r e c i p i t a t i o n e f f e c t i v e n e s s data, much b e t t e r than the production reached on Premier Ridge. The two s e l e c t i v e l y logged s i t e s had a,n annual increment of 38 f t 3 and 27 f t , 3 . The young lodgepole s i t e has an annua1 growth r a t e of 68 f t 3 of timber per year per acre. The d i f f e r e n c e between Premier Ridge and E s t e l l a Mountain ca.n l a r g e l y be a t t r i b u t e d to the increased e l e v a t i o n of the l a t t e r and the consequences of e f f e c t of microclimate. The increased summer r a i n f a l l , extends the growing season a.nd although the temperatures are lower, the a v a i l a b l e and e f f e c t i v e moisture i s much gr e a t e r than i t i s f o r Premier Ridge. The net pr o d u c t i v i t y of the understory on E s t e l l a 127 g e n e r a l l y d e c l i n e s as the succession progresses. An i n -crease i n y i e l d i s noted i n the youngest stage of the r e -generation c y c l e s t u d i e d . This i n c r e a s e was e n t i r e l y due to a high y i e l d hy bearberry. Those components which may b considered u s e f u l to n a t i v e ungulates, the grasses, forbs and dwarf shrubs, g e n e r a l l y d e c l i n e i n y i e l d as the f o r e s t regeneration proceeds. While grass production may be moderate under some f o r e s t stands, the species composition (mainly pinegrass) i s not s u i t e d to w i n t e r i n g ungulates. Trad i t lona], l y , s t u d i e s which have compared the e f f e c t of the f o r e s t on understory p r o d u c t i v i t y , have el i m i n a t e d the s u c c e s s i o n a l element i n an attempt to remove as many v a r i a b l e s as p o s s i b l e . Pase ( 1 9 5 8 ) com-pared the herbage production and species composition under immature ponderosa pine i n the Black H i l l s . Stand age was held constant, but a r t i f i c i a l t h i n n i n g had produced stands va r y i n g i n f o r e s t canopy from 0 $ to 7 1 $ and wi t h a base area from 0 to 215 f t 2 per acre. Pase ( i b i d ) found that grass production on open (unforested) areas was 74 times greater than wa.s produced i n stands which had a b a s a l area of 215 f t 2 per acre. Forbs and shrubs were a l s o i n t o l e r a n t to increased f o r e s t canopy, producing l e s s than 5 0 l b / a c . of a i r - d r i e d forage under a canopy of 7 1 $ . H a l l s and Schuster (19^5) s t u d i e d herbage production i n pine-128 hardwood f o r e s t s i n Texas, measured herbage, f o r e s t cover percent and t r e e b a s a l area but made no mention of the age of the stands or t h e i r s u c c e s s i o n a l status.. Despite a con s i d e r a b l e volume of l i t e r a t u r e , the concept of a balance between the f o r e s t and i t s understory has not been c l o s e l y examined. I n d i v i d u a l i n v e s t i g a t i o n ( u s u a l l y proponents of one theory) have reported the r e s u l t s of experiments designed to show that e i t h e r l i g h t or r a i n f a l l l i m i t understory p r o d u c t i v i t y conversely, B a r r e t t ( 1 9 6 5 ) . B a r r e t t and Youngberg ( 1 9 6 5 ) have shown that a heavy understory i n h i b i t s or minimizes wood pro-duction. McConnell and Smith (1 9 7 0) reported that t h i n n i n g dense (2,800 stem/ac.) stands of ponderosa pine r e s u l t e d i n dramatic increases i n understory p r o d u c t i v i t y eight years f o l l o w i n g the t h i n n i n g . These r e s u l t s suggest that there may be a c t i v e competition f o r some m a t e r i a l , p o s s i b l y water or n u t r i e n t s , between the f o r e s t and the understory. In a d d i t i o n to the annual y i e l d of a. piece of land there i.s a l s o a. "maintenance c o s t " which must be considered. This could be recognized as the energy required to maintain the pla n t biomass a l i v e during the year. On the unforested areas the t o t a l p r o d u c t i v i t y i s channelled i n t o the production of grasses, forbs and shrubs; the l a r g e s t part of which i s .available to gr a z e r s . 129 As f o r e s t regeneration commences and the timber matures, more and more of the n u t r i e n t s are taken up by the f o r e s t to form the new growth and to maintain the e x i s t i n g volume of l i v i n g t i s s u e . Hence there are l e s s n u t r i e n t s f r e e l y a v a i l a b l e to the understory community.' Grasses and forbs : do not expend much energy maintaining the previous year's growth above the ground surface. Shrubs,•• h o w e v e r d o r e -qui r e some energy to maintain the t i s s u e s developed i n previous years. The volume of t h i s t i s s u e , on a u n i t area b a s i s , i s much l e s s than f o r t r e e s . As v e g e t a t i o n progresses from open rangeland to timbered range, each succeeding year sees more and more energy and n u t r i e n t s t i e d up i n the maintenance and growth of the t r e e s . I r r e s p e c t i v e of the e f f e c t s of the f o r e s t canopy on the understory i t i s not s u r p r i s i n g that under-s t o r y p r o d u c t i v i t y decreases as the biomass of the trees inc r e a s e s . There i s no question that as a succession pro-gresses from unforested to f o r e s t e d land, a dramatic de-crease i n the xanderstory takes p l a c e . Furthermore, t h i s d e c l i n e i s most apparent i n that part of the community which i s g e n e r a l l y recognized to be of most b e n e f i t to g r a z i n g animals. A l l but a few of the c r i t i c a l w i l d l i f e winter ranges which occur on the f l o o r of the southern Rocky 130 Mountain Trench are p o t e n t i a l l y f o r e s t . Tree regeneration has begun on a l l of these areas and i s w e l l underway on Premier Ridge. As the open unforested range acreage s h r i n k s a n n u a l l y , the gr a z i n g pressure on the remaining open areas becomes more intense. Many communities, p a r t i c u l a r l y those near water and on l e s s steep t e r r a i n are already over-grazed. There i s a value to the timber which w i l l develop on many areas, p a r t i c u l a r l y the north and northeast slopes. The p e r i o d between cuts on the south and southwestern aspects i s about 200 years. The economic value of such a harvest i s probably very small when considered on an annual b a s i s . I f f o r e s t regenerates on the c r i t i c a l slopes, the option of w i l d l i f e to use the vast a l p i n e summer ranges i n the heart of the Rocky Mountains ( l a r g e l y untouched by man at present) w i l l be l o s t . This would g r e a t l y decrease the " u s e f u l " p r o d u c t i v i t y of these a l p i n e areas from the standpoint of human b e n e f i t , to both consumptive and non-consumptive users of the resource. In a d d i t i o n , I f regeneration continues, s u b s t a n t i a l summer ranges f o r c a t t l e w i l l be l o s t and marginal ranches of the area w i l l be unable to repla c e these g r a z i n g areas i n a v a l l e y where i n d u s t r y and human pop u l a t i o n are i n c r e a s i n g r a p i d l y . 131 REFERENCES CITED Anderson, R. C , 0 . L. Loucks and A. M. Swain. 1 9 6 9 . Herb-aceous response to canopy cover, l i g h t i n t e n s i t y , and t h r o u g h f a l l p r e c i p i t a t i o n In c o n i f e r o u s f o r e s t s . Ecology. 5 0 ( 2 ) : 2 5 5 - 2 6 3 . A r n o l d , J . F. 1 9 5 0 . Changes i n ponderosa p i n e bunchgrass ranges i n N. A r i z o n a r e s u l t i n g from p i n e r e g e n e r a t i o n and g r a z i n g . J . F o r e s t r y 48 :118-126. B a r r e t t , J . W. 1965. Spacing and u n d e r s t o r y v e g e t a t i o n a f f e c t growth of ponderosa pine s a p l i n g s . P a c i f i c N.W. F o r e s t and Range Exp. Sta. U. S. Rep. Agr., F o r e s t Serv. Res. Note PNW 2 7 , 8 p. Center f o r N a t u r a l Resources (ed). 1 9 6 9 . C o n i f e r o u s F o r e s t s of the Northern Rocky Mountains. U n i v e r s i t y o f Montana Foundation, M i s s o u l a . 395 PP • Daubenmire, R. F. 1 9 4 3 . V e g e t a t i o n a l z o n a t i o n i n the Rocky Mountains. Bot. Rev., 9 : 3 2 5 - 3 9 3 . _____ 1 9 4 6 . The l i f e - z o n e problem i n the n o r t h -ern intermountain r e g i o n . Northwest S c i . 2 0 : 2 8 - 3 8 . . 1 9 5 9 . A canopy coverage method of v e g e t a t i o n a l a n a l y s i s . Northwest S c i . 3 3 * 4 3 - 6 4 . Demarchi, D. A. 1 9 6 8. Ecology of the Premier Ridge b i g h o r n w i n t e r range. Mimeo Report to B. C. F i s h and W i l d l i f e Branch. 35 P• Dodd, C. 1 9 6 9 . The r e l a t i o n s h i p of herbaceous u n d e r s t o r y growth to t r e e o v e r s t o r y . 75 pp. B.Sc. T h e s i s , Univ. of B. C. Dept. of P l a n t Science. E h r e n r e i c h , J . H. and J . S. Crosby, i 9 6 0 . Herbage pro-d u c t i o n i s r e l a t e d to hardwood crown cover. J . F o r e s t r y 5 8 : 5 6 4 - 5 6 5 . Gaines, E. M., R. S. Campbell and J . J . B r a s i n g t o n . 1 9 5 4 . F o r e s t p r o d u c t i o n on l o n g l e a f pine lands of southern Alabama. E c o l . 3 5 : 5 9 - 6 2 . G a r r i s o n , G. H. i 9 6 0 . Recovery of ponderosa p i n e range i n e a s t e r n Oregon and eastern Washington by the 7 t h year a f t e r l o g g i n g . Proc. Soc. Amer. For. i 9 6 0 , I96I: pp. 1 3 7 - 1 3 9 . 132 H a l l s , L. K. and J . L. Schuster. 1 9 6 5 . Tree-herbage r e l a t i o n s i n the pine-hardwood f o r e s t s of Texas. J . F o r e s t r y 6 3 ( 2 ) : 2 8 2 - 2 8 3 . Jameson, D. A. 1 9 6 7 . The r e l a t i o n s h i p of tre e o verstory and and herbaceous understory v e g e t a t i o n . J . Range Man. 2 0 ( 4 ) : 2 4 7 - 2 5 0 . K e l l y , C. C. and P. N. Sprout. 1 9 5 6 . S o i l survey of the upper Kootenay and Elk R i v e r v a l l e y s . Report No. 5 B r i t i s h Columbia S o i l Survey. 99 p. McConnell, B. R. and J . G. Smith. 1 9 7 0 . Response of under-s t o r y v e g e t a t i o n to ponderosa pine t h i n n i n g i n eastern Washington. J . Range Man. 2 3 ( 3 ) : 2 0 8 - 2 1 2 . Ormerod, D. W. 1 9 6 8 . Improved instrumentation f o r e s t i -mating three crown h o r i z o n t a l dimensions by v e r t i c a l p r o j e c t i o n . Unpubl. B.S.F. Thesis. Univ. of B r i t i s h Columbia. 44 p. Pa.se. C. P. and R. M. Hurd. 1 9 5 8 . Understory v e g e t a t i o n as rela.ted to b a s a l area, crown cover and l i t t e r produced by immature ponderosa pine stands i n the Black H i l l s . Soc. Amer. Foresters Proc. 1 9 5 7 : 1 5 6 - 1 5 8 . Quaedvlieg. M. T. 1 9 6 9 . P r o d u c t i v i t y , age and general ecology of b i t t e r b r u s h on the B u l l R i v e r and Premier Ridge ranges. B. Sc.A. Thesis, Dept. of Plant S c i . Univ. of B r i t i s h Columbia. Runka, G. B. 1 9 7 0 . Lands of the East Kootenay. Report to the B.C. S o i l C a p a b i l i t y f o r A g r i c u l t u r e and F o r e s t r y Committee. Mimeo. 180 p. Smith, J . H. G. and R. E. Breadon, 1 9 6 4 . Combined v a r i a b l e equations and volume-basal area r a t i o s f o r t o t a l cubic foot volumes of the commercial t r e e s of B. C. For. Chron. 40(2) : 2 5 8 - 2 6 l . Stokes,, M. A. and T. L. Smiley. 1 9 6 8 . An i n t r o d u c t i o n to tree r i n g d a t i n g . Chicago, Univ. of Chicago Press 1 - 7 3 -Westlake. D. G. 1 9 6 3 . Comparisons of p l a n t p r o d u c t i v i t y . B i o l . Rev. 3 8 ( 2 ) . - 3 8 5 - 4 2 5 . 133 Young; J . A., J . A. B. McArthur and D. W. Hedrick. 1 9 6 7 . Forage u t i l i z a t i o n i n a mixed-coniferous f o r e s t of northeastern Oregon. J . F o r e s t r y 3 5 : 3 9 1 - 3 9 3 . • 134 APPENDIX I The p h y s i c a l c h a r a c t e r i s t i c s of the s i t e s on Premier Ridge and E s t e l l a Mountain. Premier Ridge S i t e Name Aspect Skookumchuck P r a i r i e N i l R e l i c t Bunchgrass 260° B i t t e r b r u s h ' 260° Poa - S t i p a 270° Young Douglas F i r 270° Middle-aged Douglas F i r 250° Mature Douglas F i r 5.0°' Young Ponderosa Pine 0 Middle-aged Ponderosa Pine 2 1 0 ° Climax Ponderosa Pine 260° Lodgepole Pine 0 E s t e l l a Mountain S e r a i Bunchgrass 240° S e r a i Fescue 260° Regenerating Douglas F i r 290° Larch 280° Lodgepole Pine 260° % Slope E l e v a t i o n In Feet 0 2 , 6 1 0 43 3 , 4 7 5 31 3 , 1 5 0 30 2 , 9 2 0 l l 3 , 0 9 0 18 3 , 0 5 0 45 3 , 2 0 0 3 3 , 0 1 0 13 2 , 9 2 0 28 2 , 8 8 5 4 2 , 9 7 0 6o 6 , 2 0 0 47 5 , 9 5 0 5 4 , 1 7 0 33 4 , 2 2 0 45 5 , 9 8 0 APPENDIX I I Key to the s i t e s on Premier R i d g e , map on next page. 1 Mature Douglas f i r 2 Young Douglas f i r 3 Middle-aged Douglas f i r 4 Young ponderosa p i n e 5 Middle-aged pondrosa p i n e 6 Lodgepole pine 7 Poa-Stipa (unforested) 8 B i t t e r b r u s h ( P u r s h i a ) u n f o r e s t e d 9 Bluebunch wheatgrass u n f o r e s t e d 135 APPENDIX I I I • . L i s t of p l a n t s found on the study-names l i s t e d . S c i e n t i f i c Name Grasses Agropyron splcatum v a r . inerme Bromus tectorum  Festuca s c a l r e l l a  K o e l e r i a c r i s t a t a  Poa compressa  Poa p r a t e n s i s  S t i p a columhiana  S t i p a r l c h a r d s o n i  S t i p a w i l l i a m s o n l i Forbs A c h i l l e s m i l l e f o l i u m  A l l i u m cernnum  Anaphalls margarltocea  Anemone mult.if i d a  Anemone patens  Antennaria racemosa  Arabis drummondii  A r n i c a c o r d i f o l i a  Aster consplcuus ' areas; common and s c i e n t i f i c Common Name Beardless wheatgrass or bluebunch wheatgrass• Downy brome, downy chess Rough fescue Junegrass Canada bluegrass Kentucky bluegrass Columbia needlegrass Richardson needlegrass W i l l i a m s needlegrass Yarrow Nodding onion Globe anemone Pas que flower • Drummond's rockeress H e a r t - l e a f a r n i c a Large purple a s t e r or showy a s t e r A stragalus miser Timber milk vetch 137 Balsamorhiza sa g i t t a t a  Calochortus elegans  Calochortus macrocarpus  Calypso bulbosa  Componula r o t u n d i f o l l a  Carex spp. Castille.ja minlata  Crepls atrabarba  Ep 1 lob ium minatum  Erigeron compos!tus Erigeron f i l l f o l l u s  Erigeron speceosus  Eriogonum umbellaturn  G a l l i a r d i a a r s t i t a  Gent1ana amarella  Geum t r i f l o r u m  Hedysarum sulphurescens  Hieraclum albiflorum  Hierocium umbellaturn  Lesquerella Douglasii  Lewisia red!viva  Linum lewis s i  Lithospermum ruderale  Lomatium macrocarpum Spring sunflower Elegant mariposa l i l y Green banded mariposa False lady s l i p p e r Bluebell Various sedges Indian paintbrush Fleaban e Sulphur eriogonum Blanket flower White hawkweed B i t t e r root Wild f l a x Puccoon 138 Lomatium t r i t e r n a t u m  Oxytropxas c o m p e s t r l s  Penstemon p r o c e r u s  P h a c e l i a s e r v i c c a  P h l o x c a e s p i t o s a  PolemonIum p u l c h e r r i m u m  Pyrola. secunda  Sedum spp. Sene c i o canus  S i s y r l n c h i u m spp. S a i l d a g o m u l t i r u d i a t a  Stenonthlum O c c i d e n t a l e  Trapapogon d u b l u s  V i o l a , a dune a  Zygadenus elegans  Zygadenus yenenosus Dwarf Shrubs A m e l a n c h i e r a l n i f o l i a .  B e r b e r i s n e r v o s a  L i n n a e a b o r e a l i s  Rosa gymnoca.rpu  S p i r a e a l u c i d e a . N a r r o w - l e a v e d p a r s l e y Locoweed L i t t l e f l o w e r penstemon Mountain p h a c e l i a T u f t e d p h l o x S tonecrop B l u e eyed g r a s s Bronze b e l l s O y s t e r p l a n t B l u e v i o l e t M ountain death camas Death camas Saskatoon b e r r y ( s e r v i c e b e r r y ) Mahonia o r Oregon grape Twin f l o w e r Dwarf r o s e F l a t - t o p s p i r a e a 1 3 9 Other Shrubs Arctostaphylos Uva-ursl  Clematis Columbiana  Phlladelphus l e w i s l i  Purshia t r i d e n t a t a  Shepherdia canadensis  Symphorlcarpus a l b a K i n n i k i n n i k or bearberry Blue clematis Mock orange B i t t e r b r u s h S o a p o i a l l i e , bearberry Snowberry 

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